right now. from nbc news world headquarters in new york, this is "nbc nightly news" with lester holt. good evening. donald trump who has repeatedly decried negative media coverage of him, as part of a rigged system, has once again made himself the top of the news cycle for going where no presidential candidate has gone before. at a rally in ohio today, trump first mocking and then trying to qualify his jaw-dropping response debate, about whether he would accept the outcome of the election. his refusal to say managed to irk even some of his most ardent supporters, while shifting the focus from what many believe was his best debate performance. nbc's katy tur leads off our coverage. >> ladies and gentlemen, i want to make a major announcement. >> reporter: donald trump is refusing to play by the rules. >> -- that i will totally accept the results of this great if i win. >> reporter: making it clear the only outcome he will accept is the one that puts him in the white house. >> i would also reserve my right to contest or file a legal challenge in the case of a questionable result. >> reporter: a defiant double-down from last night's debate. >> do you make the same commitment that you will absolutely -- result of this election? >> i will look at it at the time. i'm not looking at anything now. >> are you saying you're not prepared to stick to that principle? >> what i'm saying is, i'll tell you at the time. i'll keep you in suspense. >> reporter: trump reversing a vow he made just last month. during the first debate. >> will you accept the outcome of the election? >> if she wins, i will absolutely support her. >> reporter: trump supporters all in, but outside of trump's orbit, a flood of condemnation. >> when you try to sew people's minds about the legitimacy of our elections, that undermines our democracy. >> i don't believe that there's a rigged election system. >> reporter: and the north carolina gop, which said it was not aware election results were optional. >> what donald trump is doing right now is damaging that system, hopefully not beyond repair. >> reporter: the campaign's new spin, al gore did it too. but back in 2000, gore never questioned the integrity of the process before the ballots were cast, and the recount was automatically law, given how close the race was. trump's campaign staking its candidacy on easily refuted claims, from the rigged election, trump's iraq war stance, and russian hacking. >> she has no idea. >> it's time for you to stake a stand. >> whether it's russia, china, or anybody else. >> i am not quoting myself. >> she has no idea. >> reporter: today the intelligence community pushing back hard. director of national intelligence, reasserting russia was confident, you know, i think it's speaks for itself. >> reporter: nbc news has learned from government sources trump was even briefed on russia's involvement with the hack in his national security briefings, three weeks after he openly asked putin's government to find clinton's missing e-mails. >> russia, if you're listening, i hope you're able to find the 30,000 e-mails that are missing. >> reporter: less than 24 hours after that contentious debate, both donald trump and hillary clinton will be here, attending the charity dinner, where the only thing separating them will be a priest. cardinal timothy dolan, seating right between them. lester? >> all right, katy tur, thanks. trump and clinton, at a potentially tense and awkward affair colonel suffer what happened on that stage last night. at times, things got personal. heated moments that included the kind of name-calling we've never quite heard in a presidential debate from nbc's andrea mitchell. >> reporter: it was downright brutal and personal. >> she's been proven to be a liar. >> rather have a puppet as president. >> no puppet, you're the puppet. >> reporter: fight night in vegas where the biggest impact white be on the critical female swing voters. donald trump using graphic language to fire up conservatives, attacking hillary clinton on abortion. >> based on what she's saying and based on where she's going and where she's been, you can take the baby and rip the baby out of the womb in the ninth month, on the final day. acceptable. >> reporter: clinton relishing her first chance to go after trump about his female accusers, looking to get under his skin. >> he said that he could not possibly have done those things to those women because they were not attractive enough for -- >> i did not say that. >> -- them to be assaulted. >> i did not say that. >> donald thinks him look better. >> reporter: trump returning fire. >> she mentions this, which is all fiction. all fictionalized, probably, possibly started by her and her very sleazy campaign. but i will tell you what isn't fictionalized, are her e-mails. >> reporter: then the moment the clinton team was hoping for. an insult they think will drive women away. >> such a nasty woman. >> reporter: how did you feel when he said, nasty woman, nasty woman, and you're a puppet. >> i just didn't pay any attention to that. >> reporter: it quickly turned into a meme on twitter compared to a janet jackson song. trump even taking >> nobody has more respect for women than i do. nobody. nobody has more respect -- >> please, everybody. >> reporter: late today, michelle obama, clinton's best surrogate, going after trump too. >> decent men do not demean women, and we shouldn't tolerate this behavior from any man, let alone a man who wants to be the president. >> reporter: a problem for trump who went into the debate tied with clinton among white women, but overall. >> there's nothing that i saw in his. performance last night that leads me to believe he's going to do any better among women voters than he's doing right now. >> reporter: with only 19 days left, the clinton campaign cannot hide its glee, because they believe there's not enough time for trump to bring those women voters back to his side. >> andrea mitchell, thank you. turning now to nbc's political analyst, nicole wallace. you are a veteran of tough campaigns. trump needed a breakthrough night last night. did ar though? >> oh, just a little, lester. the poll numbers that were up at the end of andrea's piece tell you everything you need to know if you want to determine whether or not a republican can win a national election. the last time it happened, was 2004. george w. bush did that by narrowing that gender gap. he got the married women, he got the mom vote, something i've been tracking during the general election. and donald trump pushed them much further away. we have to take into terms of understanding what resonates beyond the beltway, but calling her a nasty woman, interrupting her the whole time, essentially morphing into the "snl" caricature of himself really sets in as a terrible image for donald trump among the kinds of voters he needs to sway. >> but think about the first 30 minutes of the debate. a much more subdued donald trump, and getting into substantive issues, supreme court, very important to voters. >> yeah. >> at that point, did >> well, it was his best performance. it was his best debate, but as he said last night, it was also her best debate. so she's almost in another league, in terms of her ability to communicate and now defend her own ideas. so i think she did a better job. she has vulnerabilities too. these are the two most unpopular candidates we've seen on either side, as chuck todd keeps reminding us. but she's done a much better job defending herself. while he got off to a solid start for him, on the curve that we've graded him on, this point. >> nicole, thank you very much. turning now overseas where a u.s. service member was killed in iraq today by a roadside bomb. he's the first american to die in the u.s.-backed offensive to drive isis out of mosul, according to a senior defense official. tonight our richard engel is on the front lines with iraqi forces and brings us an extraordinary look at the underground tunnel network isis used to prepare for this battle. >> reporter: iraqi and kurdish forces today push toward mosul. the main offensive was from the east and to the town of bartella, just over ten miles from the city. we climbed into one of the iraqi special forces old american humvees. it's battle-worn, shot up, and the driver said damaged by an isis suicide bomber today. then it was on foot. quickly, because rounds whizzed by. christian village is one of isis's main defensive positions leading towards mosul, and they're fighting hard to keep it. isis sending out car bombs. but iraqi troops are advancing faster than u.s. commanders anticipated. we'll be in mosul in two days, a soldier boasted. but isis has had two years to prepare for this fight. the soldiers showed us a tunnel they had just found. this was an isis escape route. also seems to be like one of their isis fighters lived here, safe from u.s. warplanes. just based on the number of mattresses we've seen, this could have held, 20, maybe 50 people, more if they packed them in. the tunnel extended for about a half a mile. at the far end, we came up into what appeared to have been an isis headquarters. food still in the kitchen area. half-made bombs too. and chemicals for more. flag was once enough to send the iraqi army running. that's how isis took mosul. now it's isis on the run. tonight, iraqi forces have taken bartella, putting them within striking distance of mosul. lester? >> richard engel in iraq tonight, thank you. in arizona, this evening, police have released 911 calls connected to an unsolved serial killing spree that is still baffling investigators. after at least nine separate shootings, seven people, the phoenix area. there have been thousands of new leads, but no arrests. we get the latest from nbc's miguel almaguer. >> phoenix 911, where is your emergency? >> um, he's shot on the floor. yes, it's my brother. he's been shot. >> reporter: the heart breaking call for help from one family targeted by arizona's serial killer. >> they pulled up in front of our house, i guess, and they shot kids. i have two babies here. >> reporter: after seven people were killed, including a 12-year-old girl, phoenix police now releasing chilling 911 calls, hoping to generate new leads in a case gone cold. nancy pena, who lost her brother horatio, can't bear to listen to the calls. >> these families are having to rehear it, relive it. it's gut-wrenching. >> reporter: the killing spree began in march. witnesses helped no arrests in this community on edge. >> he comes up at night. you get out of your car, he shoots you. >> reporter: a $75,000 reward and more than 3,000 tips, but the sketch, the only solid lead. >> when you see someone as prolific as this shooter, or these shooters have been, i think law enforcement knows it's highly likely they could strike again. >> reporter: tonight investigators hoping for a break in the case. they have the face of a killer. >> he's only 21. >> reporter: and now the sound of the heartbreak he's left behind. miguel almaguer, nbc news. there is late word this evening of another death connected to those exploding takata air bags. the national highway traffic safety administration says a 50-year-old woman died from injuries in a crash on september 30th, while driving a honda civic that was first recalled in 2008. the repair never completed. the 11th confirmed bag inflators. still ahead tonight, every homeowner's nightmare. the foundation of your house crumbling under your feet. why it's happening to so many homes and why it's time to double-check your insurance policy. also buyer beware. why apple says it's -- think twice before shopping for its products on amazon. -- think t products on amazon. think twice before shopping for its products on amazon. think twice before shopping for its products on amazon. think twice before shopping for its products on amazon. think twice before shopping for its products on amazon. i'm terrible at golf. he is. but i'd like to keep being terrible at golf for as long as i can. new patented ensure enlive has hmb plus 20 grams of protein to help rebuild muscle. new ensure enlive. always be you. our special today is the seared ahi tuna. don't you hate that? when they don't tell you how much something costs and you have to ask? maybe that's why i always make sure to... ... ?bring up the costs associated with your services.? i know. transparency about costs. back now with a consumerrt many as 30,000 homes are facing an issue so serious that the governor wants fema to declare it a natural disaster. and the effects could cost up to a billion dollars. homeowners are watching their concrete basement walls crumble, putting their houses at risk of collapse and in what could be a wake-up call for people everywhere, the insurance company say the problem isn't covered. here's nbc's stephanie gosk. >> we started hearing popping noises >> reporter: the noises were so strange the parokios had no idea what was going on, until vince went down to the basement. >> oh, my god. >> and this has probably happened in the past year. >> reporter: the middle of the night sounds were the walls of the basement splitting. >> you can see outside. >> reporter: in some places, wide open. are you worried at night the house is going to come down on top of you? >> i worry. i do worry. >> how do you sleep? >> some nights it's >> reporter: the parokios, whose house was built 30 years ago, are not alone. there's something rotten in the foundations in northeastern connecticut. >> i have nightmares. >> reporter: engineer bill neil has told hundreds of families their homes are unsafe. do you have any sense the scale of this problem right now? >> my best guest is 10- to 15,000 houses. >> reporter: in every case, the problem is traced back to one local quarry and the j.j. mottes. in a statement, they raise the possibility that the concrete was installed improperly by contractors, but experts say the problem is a mineral call piro type, found in the quarry. after years of exposure to water and oxygen, it expands, causing the cracks. there is a fix. lifting the home completely off the foundation and pouring a new one. for the parokios who raised four children here, the price tag is nearly 60% the value of their home. so they turned to their homeowner's insurance. the claim was denied. an industry spokesman said basic homeowners insurance doesn't cover the problem. >> the loss is occurring because of defective construction materials and or shoddy workmanship. no matter what state you go to, homeowner's insurance claim is not going to be paid out. >> reporter: the company. meanwhile, their house continues to crumble. >> people say, why don't you just move out? well, it's my home. >> reporter: on top of the emotional pain this family and many like them face financial ruin, and there's little hope of a quick solution. stephanie gosk, nbc news, willington, connecticut. we're back in a moment with why snoopy, charlie brown, and the rest of the peanuts gang are down a gig tonight. found a better l on prescriptions. we found lower co-pays... ...and a free wellness visit. y. it's medicare open enrollment. have you compared plans yet? it's easy at medicare.gov. or you can call 1-800-medicare. medicare open enrollment. you'll never know unless you go. i did it. you can too. ? ? i am totally blind. i lost my sight in afghanistan. if you're totally blind, calling 844-844-2424. or visit my24info.com. our eyes they have a 200-degree range of sight which is good for me hey! and bad for the barkley twins. take care of all your most important parts with centrum. upgraded to our most d3 ever. ? it's not uncommon for autistic kids to flap their hands. my son max can't live in trump world. so i'm crossing party lines and voting for hillary. i don't always agree with her, but she's reasonable. and she's smart. she can work with people to solve problems. i want to be able to tell my kids that i did the right thing when it really mattered. i'm hillary clinton and i approve this message. look at all these purchases you made with your airline credit card. hold on...you only got double miles on stuff you bought from that airline? the capital one venture card. with venture, you earn unlimited double miles on every purchase... not just...(dismissively) airline purchases. every purchase. everywhere. every day. no really! double miles on all of them! we're back with warning for online shoppers. apple says it's been buying up chargers and cables labelled as genuine apple products on amazon and found nearly 90% are counterfeit. apple is suing the seller, mobile star. apple warns the knockoffs pose a significant risk of overheating, fire, and electrical shock. mobile star did not respond to our request for a comment. and good grief, snoopy just got canned. metlife is saying character after more than 30 years of helping met life connect with its customers in advertising. the move comes as the company spins off most of its u.s. insurance operations, instead focusing on corporate and international business, marking the end of an era for snoopy. soon america will have to say bye-bye to bao bao, the giant panda born in the national zoo in washington, d.c. three years ago. her parents were on loan from china and, under that agreement, she'll be sent to announced its 3-year-old giant panda twins will be sent to china in two weeks. when we come back, a teen whose unbreakable bond with her younger brother has inspired a potentially i had frequent heartburn, but...my doctor recommended prilosec otc 7 years ago, 5 years ago, last week. just 1 pill each morning. 24 hours and zero heartburn, it's been the number 1 doctor recommended brand for 10 straight years, and it's still recommended today. use as directed man: i accept i even accept i have a higher risk of stroke due to afib, a type of irregular heartbeat not caused by a heart valve problem. but i won't go after anything with less than my best. so if i can go for something better than warfarin, i'll do that too. eliquis. eliquis reduced the risk of stroke better than warfarin. plus, it had significantly less major bleeding than warfarin. eliquis had both. that's what i wanted to know. don't stop taking eliquis lls you to, as stopping increases your risk of having a stroke. eliquis can cause serious and, in rare cases, fatal bleeding. don't take eliquis if you have an artificial heart valve or abnormal bleeding. while taking eliquis, you may bruise more easily. and it may take longer than usual for any bleeding to stop. seek immediate medical care for sudden signs of bleeding, like unusual bruising. eliquis make increase your bleeding risk if you take certain medicines. tell your doctor about all planned medical or dental procedures. and for eliquis. reduced risk of stroke, plus less major bleeding. ask your doctor if switching to eliquis is right for you. plus - a schmorgasboard of your ballot errors - what happens if your county makes a mistake? what is you make a mistake? all questions answered! on next. finally tonight, finally tonight, we have a remarkable story about the bond between a teenage girl and her little brother. a love that remains so strong even through tragedy and now they've inspired a project that could help millions of other families. here's gadi schwartz. ? i'd like to make myself believe ? >> reporter: at age 7, tanner longstreet helped put blush on his sister's cheeks. >> he's actually pretty good. >> reporter: at 8, he was her dancing >> reporter: but at the age of 10, tanner was diagnosed with brain cancer and died the next year. >> i didn't do anything, was the words that came out of his mouth. and that breaks my heart. >> reporter: tanner had a mutated gene, called tp-53, that can ltd to several forms of deadly cancer. when tested, the same muteration showed up in his father and his sister casey. >> what are your chances of getting cancer? >> i couldn't be more proud of someone who faces what she faces. she held her brother during his last breath and she knows what she's up against efrl single day. >> reporter: now casey is the sole subject in a ground-breaking dna study they've named the tanner project, in memory of her brother. >> i think she's a great example for the world. >> reporter: she's working with doctors like craig vinter, the first person to sequence the human genome. >> pioneers like casey help us because we'll find out from all the tests, whether she's develops something early on, or whether she never develops it. >> reporter: can live with the same genetic mutation that took her brother's life. >> i'm used to it. >> reporter: they're also monitoring for the earliest signs of disease. so far -- >> everything looks good. >> reporter: -- no cancer. which means she's free to be a normal teenager. she's started a project called genome generation to honor her brother's memory and encourage others to consider genetic testing. >> he taught me so even before he was sick. he's the reason why i am who i am today. i love you. >> reporter: a bond with her little brother that remains unbroken. gadi schwartz, nbc news, los angeles. >> what a great story. that's going to do it for us on a thursday night. i'm lester holt. for all of us at nbc news, thank you for watching and goodnight. i'm lester holt. for all of us at nbc news, thank you for ?[ remember the good old days? all the votes were cost on election day. all the confusion was handled by those sweet, understanding poll workers? now you're confused and you're stuck with "next" with your questions. you're not the only confused. mistaking their commissioner. should we boo barack? a fair question. and that kind of universal language could be useful in a school with 40 different languages. si. and it's "next." doublecheck your ballot before you mail it and don't let it out with a mistake like douglas county did! just a missing "m" in "commissioner." if you vote in those -- they swear half a dozen people spellcheck that thing. >> very fortunately it wasn't a name. if we had misspelled a name, it would have been beyond not good. when i proof a ballot, i focus on the names. the rest of it reads and i