>> reporter: mitt romney went to church but this sunday wasn't a day just for prayers. it's preparation. cramming by the candidates for their big debate. and republican chris christie made a bold prediction on abc's "this week." >> every time mitt romney has been confronted in this campaign with one of these moments, he has come through in the debate and performed extraordinarily well so i have absolute confidence thursday morning you'll shake your head saying it's a brand-new race. >> reporter: christie is way off the romney campaign script. they're trying to lower expectations. >> look, president obama is a very -- he's a very gifted speaker. the man has been on the national stage for many years. this is mitt's first time on this kind of stage. >> reporter: paul ryan, the vice presidential nominee preparing for his own debate avoided giving details much the tax plan even when pressed. >> haven't given me the math. >> i don't have the -- it would take me too long to go through all of the math. >> reporter: the president is in nevada at any time for what insiders call three days of debate camp at a resort outside of las vegas. they too are trying to lower expectations and believe the count that the romney campaign is convinced debates are about moments. >> the idea that i'm anti-immigrant is repulsive. >> reporter: and romney will come armed with several one-liners. >> they've been 3r5ing zingers and lines for months. i'm sure a bunch of clever lines but that's not what the american people are looking for. >> reporter: the president is being coached to be crisper, shorten his answers and a former democratic candidate says he needs to avoid being irritable. >> he's got to relax. he's got to show it and show a little sense of humor. he's got to show why he's likable. >> reporter: the debate is set for 90 minutes on wednesday night. it's all on domestic issues, the first half, jobs and the economy, the second half, health ka'aihue and other domestic issues. david? >> david kerley in washington tonight, david, thanks very much. i want to bring in abc news political analyst matt dowd who advised both republican and democratic campaigns age that is always great to have you with us. you have three things for everyone to watch for. one of the things you point out body language could have a bigger impact on words. we remember al gore and george bush having a field day with those. >> i've had a record of that in texas. >> as if the sighing weren't bad enough gore's behavior got worse. [ laughter ] >> in that same year we remember the moment when al gore got up, walked over towards governor bush and this is his reaction. >> flying to get things done. >> and i believe i can. [ laughter ] >> famous moment, years prior there was h.w. bush checking his watch. famous moments. are these debate prep teams saying this is what you don't do. >> at this point in time they're emphasizing style as opposed to substance right now because debates have changed people's minds have been about physical characteristics and mannerisms in the modern age and not about the substance of the policy answers so paying a lot of attention to the style and not the substance. >> you can almost watch it with the debate down and determine who wins the thing. you pointed out something else, you were at the next debate. this was an image from senator kerry taking on george w. bush and say by simply showing up, the challenger has a lot to gain. >> when they stand on the same stage as the president of the united states you basically become almost an equal at that point in time and that race went from seven-point lead to a one-point lead in 48 hours and that's what the challenger was able to do. john kerry won it and took the race to almost even within two days. >> big opportunity for mitt romney this week. >> huge opportunity for mitt romney. he could take this race in the states he's losing right now and change the dynamic of the race just by standing on stage and performing well. >> so much riding on it. this first debate, anywhere between 50 million, 60 million are the stilts. this year more important than ever the early voting that's taking place. >> it's taking place in key states like iowa right now and voters willing watching this. already voting and the best thing about this debate is -- tore these guy, it's the first authentic moment and a while where voters want to tune in and pay attention. not a television ad, not a convention but a real authentic moment they take cues from. >> by election day a third of american voters might have already gone to the poll. >> campaigns used to have to plan toward one election day and now they can plan toward 30 or 35 election days and that's why this debate is crucial because voting is already going on. >> matt dowd with us in new york. matt, our thanks to you and special coverage "one on one" the candidates debate wednesday 9:00 p.m. diane and george. i'll be in denver with jake tapper and the entire team here wednesday night. we move on to washington and a memorable sight in church. six supreme court justices attending the annual red mass on the day before they begin their new term. the court expected to grapple with several hot button issues including same-sex marriage, affirmative action and the voting rights act. this will be the first time the court will be in session since that dramatic ruling last june upholding president obama's health care law. overseas now to afghanistan and a stark reminder tonight of the human cost of war. an attack at a checkpoint left two americans dead, one a serviceman. the 2,000th u.s. military death since the war began. muhammad lila is in the region tonight. >> reporter: some officials are describing this as a firefight between american troops and the very afghan soldiers they were working alongside. for reasons that aren't yet clear it appears as though there were some sort of confrontation at one of the many checkpoints american troops are often stationed at. there was an exchange of gunfire. at first the coalition called it an insider attack at the hands of afghan forces. but later they said the taliban might have been involved. now whatever the reason, the 2,000th american killed in afghanistan is certainly a very grim milestone. this comes just as we are days away from the 11-year anniversary of combat in afghanistan and there is another number to consider, 68,000 american troops are now in afghanistan increasingly under threat not just from theiren economies but also their so-called allies. david? >> muhammad lila in the region, thank you. and from the war in afghanistan to an eruption of deadly violence in iraq, 26 people were killed in more than 90 injured by a wave of bombings targeting security forces in shiite neighborhoods. officials blamed al qaeda in iraq which has been trying to undermine their fragile government. and in spain tonight at least 12 people have been injured when riot police clashed with protesters rallying in steep cuts in government spending. the violence broke out when police at the times moved in to disperse the crowds and some responded by throwing rocks and bottles. back in this country tonight there are troubling new questions this evening about airport security. we have learned this evening that twice in the last week agents with the transportation security administration, the tsa, allowed loaded guns to through airport checkpoints. here's abc's mark greenblatt now. >> reporter: in the latest black eye for tsa, a loaded .38 caliber gun like this went undetected by screeners. new orleans hornets' executive joshua richardson says he mistakenly flue with it from new orleans to newark. just one day earlier in orlando, they missed another loaded gun. this time in a firefighter's carry-on bag. that gun made it on to the plane. >> well, scary but surprising. >> so i would say generally i have been very thorough and surprised they missed something like that. >> reporter: some in congress worry it's become business as usual. >> unfortunately, the reports i get it's not just this one weapon. it's hundreds of items every day but it can't be tolerated. >> reporter: it's more unwanted scrutiny for the agency on the heels of an investigation by abc's brian ross into possible theft by tsa agents which tracked a missing ipad to the home of this officer. >> my wife says she got the ipad and brought it home. >> reporter: that can't be true. the last time we saw it it was in your hands. >> reporter: that officer was fired but as for the record on security, the tsa said it's had many successes confiscating 1 1,100 weapons so far this year, 29 guns last week alone. but still when it cops to all the blunders many now think the tsa's own screeners need better screening themselves. >> i think it goes back to the type of hiring they did, the educational requirements that they were allowed to put in place, which were not high enough, in my view. >> reporter: now, as for that officer that led a firefighter carry a gun right through security, tsa says the person responsible has been pulled from duty this week with possibly more disciplinary action to come. david? >> mark greenblatt tonight, thank you. from tsa agents under fire to the border patrol agent now under investigation by the fbi tonight. the agent shot and killed a mother of five while she was in the driver's seat of her car and this evening there are two very different accounts of what happened just before that shooting. here's abc's reena ninan now. >> reporter: a makeshift memorial to honor a mother of five who family and friends say shouldn't have died at the hands of a u.s. border agent. >> i think we're all shocked. we want answers. >> we just want justice, that's it. >> reporter: there are varying accounts of how valeria alvarado was killed during a confrontation with a plainclothes agent serving an arrest warrant to another individual in the neighborhood. >> she stops right here, backs up a little bit. you see the guy walking from behind the car coming to the front and just shooting like ten, 12 bullets at her. >> next thing he knows he gets to the car opens the door and pulls out his badge like that. whoa, that should have been the first thing. >> reporter: local police officials have a different story. saying she drove into the agent for reasons that are still not clear. >> and literally ran our agent down. the agent actually was impacted, was hit by the vehicle and carried several hundred yards on the hood before fearing for his life. >> reporter: and police say that's when he fired his gun at least five times according to witnesses killing her. the entire incident unnerving this california community. >> yeah, i want justice. yes, whoever shot my wife, that guy, whoever he is, he needs to get shot. yeah, he needs to get justice served. you don't shoot a person. >> reporter: they went house to house searching for eyewitnesses as part of the investigation still awaiting an autopsy report. david. >> reena ninan in our washington bureau tonight, reena, thank you. now to that alarming problem overtaking some of america's lakes and we even saw it in washington, d.c. this week at the lincoln memorial where the famous reflecting pool was instead filled with clumps of green. it is happening all across this country and in some places it's making people sick. here's abc's senior fwhat correspondent jim avila. >> reporter: it's an assault on nearly all the senses -- a living, breathing, growing toxic organism known as blue-green algae -- at its worst this month. >> that's very much alive. >> gosh. it smells bad. whoo. >> reporter: caking america's lakes. so thick, the swirling slime can actually be seen in photos from space. >> people that used to be here after a couple years said we just kacht handle it anymore and left. >> reporter: tom koren runs the marina at lake petenwell, wisconsin or tries to. >> nobody wants to swim in this water, and nobody wants to boat in it. >> reporter: it not only looks bad and smells bad, it's toxic, and those who are unlucky enough to fall in without a suit like this get sick pretty fast. dan jenkins didn't even go in the lake next to his house, but his dog, casey, did. >> he's covered in this carpet of green slime. >> reporter: it made breathing difficult, and within weeks -- >> casey had started walking sideways. >> reporter: 72 hours later, he died, and his owner, d, was partially paralyzed. >> oh, it hit me hard. wobbling around like that, it would make me mad. i mean, it was a fight. >> reporter: he still hasn't recovered, and a joint investigation by abc news and the food and environment reporting network found more than 100 reported illnesses due to blue-green algae exposure. >> essentially if we don't solve this problem, somebody's going to die. >> reporter: ohio state's dr. jeffery reutter is the foremost authority on blue-green algae. he says it's a nationwide problem, largely caused by farm fertilizer runoff. the cure, he says, is convincing farmers to carefully fertilize so the nutrients stay on the fields and not in the water. >> otherwise, these blooms are going to continue to grow. the human health problems that we see are going to increase. >> reporter: assaulting our senses, our economy and our health. jim avila, abc news, lake petenwell, wisconsin. >> our thanks to jim tonight. and in los angeles, a bridge demolition that forced officials to shut one of america's busiest highways, the 405 freeway went as plan and carmageddon didn't happen. the lanes are expected to re-open as planned for the morning commute. there is still much more ahead on "world news" this sunday night. for the first time one of those replacement refs on the field that night speaking out about that controversial call that captured the attention of the entire country. what that ref is saying tonight. 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[ male announcer ] be sure to talk to your doctor before you begin an aspirin regimen. i'm a fighter and now i don't have that fear. perhaps you noticed the nfl's professional referees are back on the field today after that outrageous call at monday's packers/seahawks game. the replacement refs are probably happy to be out of the spotlight too but one member of that rue is speaking out about what it was like to watch the call unfold on that field. here's abc's john schriffen tonight. >> reporter: on three, let's go, refs? this nfl sunday the men in stripes got the unusual superstar treatment from the fans. decided to see the regular referees back in action, their labor dispute forced to an end after this blown call last week by the replacements. >> the game's final play. >> reporter: in monday's night game between the packers and seahawks the jump ball appears to be grabbed by green bay. >> who do they give it to? touchdown. feels like a jennings interception. >> reporter: but they gave the call and win to seattle sparking national outrage and ridicule. the nfl received 70,000 phone complaints. even saturday night live couldn't resist. >> time of death, 2:15. >> no, no, no, i'm not dead. also, it's 4:30. "whistle ] >> reporter: one man who wasn't laughing replace many referee mike peek on the field working that game. >> to see the game fall apart at the end, it was really one of those things that make you want to go in the back room and cry a few tears. >> reporter: although he didn't make the call this community college teacher from texas with 13 years of division i college revving experience stands by his fellow fill-ins. >> if somebody asks me a good call or bad call it depends where you live. >> reporter: it seeps they're still at the mercy of the players. coaches and fans. >> number 29, defense. first down. >> reporter: after all, all referees are still only human. as for the regular refs, they're used to fans second-guessing their calls on-the-field, but their decision to hold out earned them a new eight-year deal that increases their pay and pension, david. >> they were welcomed back today with open airports. >> in the beginning until a call went against their team. >> honeymoon short-lived. thanks. when we come back, what was it that sent this car sliding clear across the parking lot. watch this. soon it is airborne flipping over. we'll be back. 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[ male announcer ] make the switch. take action. take advil®. and if pain keeps you up, sleep better with advil® pm. an earthquake struck just outside dallas overnight rattling dishes and some nerves there. the 3.5 magnitude quake was followed by a few minutes later a 3.1 aftershock. although it hit by the dallas/ft. worth airport operations remain normal. 911 operators were flooded with calls but the damage was minimal. overseas a powerful typhoon is battering japan forcing tens of thousands to evacuate. look at this image that came in. this car in this parking lot is about to slide clear across the parking lot. the people taking the pictures can't believe what they're seeing about to flip right into the air several times. dozens of people injured in that typhoon. back in this country an inspiring homecoming at one michigan high school. solve for whitney kopp found out she had been nominated for homecoming queen and learned it was a cruel joke. that's when herfamily and friends took action with a support whitney facebook page. flowers came from all over the country and she proudly accepted her nomination. didn't win the crown but you can see she is beaming right there on the field. when we come back on the broadcast tonight why christmas has come early to one american town and when you see this 5-year-old you just might want to put up your lights too. ♪ into a scooter that talks to the cloud? ♪ or make 70,000 trades a second... ♪ reach one customer at a time? ♪ how do you help doctors turn billions of bytes of shared information... ♪ into a fifth anniversary of remission? ♪ or turn 30-million artifacts... ♪ into a high-tech masterpiece? ♪ whatever your business challenge, dell has the technology and services to help you solve it. because it helps you keep doing what you love. no wonder it's america's #1 selling pain reliever. you took action, you took advil®. and we thank you. [ female announcer ] charmin ultra soft is so soft you'll have to remind your family they can use less. it's made with extra cushions that are soft and more absorbent. plus you can use four times less. charmin ultra soft. begins with back pain and a choice. take advil, and maybe have to take up to four in a day. or take aleve, which can relieve pain all day with just two pills. good eye. wthe future of our medicare andr electiosocial security. for... man 1: i want facts. straight talk. tell me your plan... and what it means for me. woman 2: i'm tired of the negative ads and political spin. that won't help me decide. man 2: i earned my medicare and social security. and i deserve some answers. anncr: where do the candidates stand on issues that... affect seniors today and in the future? find out with the aarp voters' guide at earnedasay.org and finally tonight here it still says september on the calendar but in one virginia town it looks a lot like late december all because of a little boy's christmas wish coming true. little 5-year-old nathan norman is getting the mail and lots of it. so much so his entire family right there helping him, mom, dad, his sister there too. their mailbox already overflowing with christmas cards. >> nathan racing in to wish you a merry christmas. >> reporter: the holiday coming early for a boy who wanted it to. nathan has been fighting cancer since he was just a year old. his mom and dad and the phone calls had come at all hours of the day. >> it's never good when the doctor's office calls you after hours. >> reporter: what started as brain cancer has spread. he's had surgery and chemotherapy and he's fighting it. but his latest scan showed the tumors have been stubborn and even at 5 knowing he's up against a fight he said that the one thing that would make him happy get him through it is celebrate an early christmas. >> nathan asked when we come home if we would put up our christmas tree and our lights, that he thought that would make him feel better. >> reporter: and this weekend it wasn't just christmas at nathan's house. >> hello. >> reporter: it was christmas all through the neighborhood. the people next door putting up their christmas lights too. and indoors nathan was invited to decorate their tree. even the christmas cookies. >> sugar cookie is your shafrts, right. >> reporter: the neighbors telling little nathan and his family, we're in this together. >> we've pretty much walked this journey with him since the beginning so it was never really a question of if we were going to do it. when he asked for it to be christmas in the middle of september, you just do it. >> and so what we have right now is christmas on september 26th, 2012. >> reporter: the fight ahead for nathan, they plan on celebrating christmas with him on december 25th but they're hoping an early christmas gift and a neighborhood behind him will get him there. >> if he asks us to leave it up we may leave it up all year because in all honesty every day should be like christmas. we should always have that spirit of christmas in us. >> the virginia town where the lights and the trees will be up straight through christmas. we're pulling for nathan. that is the broadcast this sunday night. always online at abcnews.com. "good morning america" first thing in the morning and diane sawyer right back here tomorrow night. from all of us here, have a good evening. good night. i'm barack obama and i approved this message. [ mitt romney ] there are 47% of the people who will vote for the president no matter what... who are pendent upon government, who believe that they are victims, who believe that government has a respononsibility to care fothem, whbelieve that they are entitled to health care, to food, to housing, to you-name-it... and they will vote for this president no matter what... anand so my job is not to wory about thospeople. i'll never convince them they should take personal responsibility and care for their lives.