And tonight, amid growing concern within the republican establishment, a new and scathing attack on donald trump. Mitt romney calling him a phony and a fraud. Trump shooting back, calling romney a choker, a failed candidate. A remarkable change of heart between the two men, just four years ago, this moment here, shaking hands, donald trump endorsing mitt romney. Tonight, romney is now leading the charge against trump, saying trump is unfit to be president. But as some members of the party try to stop trump, what about the millions of voters who have lined up to vote for him . Theyve had their say. Abcs tom llamas leads us off with the extraordinary war of words tonight, even before the big debate. Reporter tonight, the republican establishment trying to publicly wrestle their partys nomination from donald trump. Mitt romney, leading the charge. Donald trump is a phony, a a degree from trump university. Hes playing the members of the reporter in 2012, romney gratefully accepting trumps endorsement. Magnificent hotel and having his endorsement is a delight. Im so honored and pleased to reporter four years later, campaign. This is an individual who mocked a disabled reporter, who attributed a reporters questions to her menstrual cycle, who mocked a brilliant rival who happened to be a woman due to her appearance, and who bragged about her Marital Affairs and who laces his public speeches with vulgarity. Donald trump says he admires vladimir putin, the same time, he has called george w. Bush a liar. That is a twisted example of evil trumping good. Reporter trump tonight firing back. He was begging for my endorsement. I could have said, mitt, drop to your knees. He was begging. Reporter rom knee building his case against the billionaire, saying the economy under a President Trump would be a disaster. But you say, wait, wait, wait, isnt he a huge Business Success . Doesnt he know what hes talking about . No, he suspect. And no he doesnt. His bankruptcies have crushed Small Businesses and the men and women who worked for them. He inherited his business. He didnt create it. Reporter but four years ago . Donald trump has shown an extraordinary ability to show understand how our economy works, to create jobs for the american people. Reporter the attacks just hours before the debate trump facing off against his opponents, but also against megyn kelly of fox news. A rematch after this moment youve called women you dont like fat pigs, dogs, slobs and disgusting animals. Only rosie odonnell. No, it wasnt. Your twitter account thank you. For the record, it was well beyond rosie odonnell. Yes, im sure it was. Reporter trump livid after the exchange, igniting a bitter feud with the fox news host. Theyll be face to face tonight. Tom is live from michigan tonight, and tom, first all, many who saw this today might be wondering why mitt romney, does he have any intentions of running again . Reporter david, a source close to mitt romney tells me that romney is not running for president. He had seen the race and he felt this was his best chance to get in and make a difference, to make the case against donald trump. But tom, we watched today as romney offer advice to Republican Voters in the coming states . Reporter thats right. Hes urging voters to pick other candidates besides trump to deny win the nomination outright. David, that would lead to a contested convention, where Party Leaders would choose the nominee. David . Tom llamas from a very snowy detroit tonight. Tom, thank you. Now, to the democratic side this evening, and a Major Development involving Hillary Clinton. Fueled by her super tuesday victories, we learned today the Justice Department is giving immunity to the aide who set up mrs. Clintons private server. The one she used as secretary of state. Tonight, is this good news or is this bad news for Hillary Clinton . The clinton team arguing theyve wanted that aide to speak from the start. Abcs jonathan karl, getting answers tonight. Were having such an amazing time together. Reporter Hillary Clinton seems to be riding higher than ever, following her super tuesday landslide with a starstudded fundraiser at radio city music hall. Youre gonna hear me roar reporter not just katy perty. Rocket man reporter but tonight, a double whammy. Dueling headlines on the email controversy that just wont go away. The Washington Post reporting the fbi has granted immunity to the former clinton aide who set up her private email server. Hes now cooperating with the investigation. And the New York Times now reporting the fbi could soon question Hillary Clinton herself. Shes already testified about the emails in that grueling 11hour session before the Congressional Committee investigating benghazi. Congressman, i have said repeatedly that i take responsibility for my use of personal email. Ive said it was a mistake. Reporter the Clinton Campaign says the latest developments are no big deal. That mrs. Clinton has been cooperating with the fbi, and that shes pleased her former aide is now cooperating, too. And jon karl with us live from washington tonight. And jon, when you hear about immunity, the Justice Department, emails back in the team argue this is actually a good thing . Reporter well, a top clinton adviser tells me that her legal team sees these latest moves as a soon that the fbi is getting closer to concluding its investigation, an investigation they are convinced will show that she did nothing illegal. But david, neither the Justice Department nor the fbi would have any comment at all on this today. All right, jon karl live in washington. Jon, thank you. And as the president ial candidates debate tonight, a headline breaking overseas at this hour. It comes from north korea. Jim jong unreportedly ordering the countrys Nuclear Arsenal at the ready. Reports in north korea saying the leader has ordered his military ready for a preemptive strike. This coming one day after the u. N. Security Council Unanimously approved new sanctions against north korea. Back here at home tonight, and to a case making National Headlines out of montgomery, alabama. Tension bidding after a young Police Officer was charged with murder. Shooting an unarmed black man walking home. Police saying the officer thought the man was carrying a weapon. Abcs Steve Osunsami is in mobt montgomery with the officers explanation, and the victims family now speaking out. Reporter this is the face of the young, white Police Officer arrested in montgomery, charged tonight with murdering a black man. 58yearold greg gunn. Police say 23yearold aaron smith was working third shift last thursday, patrolling a black neighborhood, when he stopped mr. Gunn, who was unarmed and walking home from a card game. There was a slight struggle that continued for about a block or so, after which time, the officer fired and shot and killed the suspect. Reporter smiths lawyer says the shooting was justified, because he says gunn was beating the officer with some sort of pipe. He thinks the arrest is all politics. We believe these charges were brought to prevent public unrest. Reporter its not lost on city leaders that this is modern civil rights movement. The march from selma to montgomery in 65 passed right through the neighborhood where gunn was killed. It really is trying our soul, as a community. Reporter were learning today that gunns father was one of the citys first black frifrs. His mother, who he lived with, was happy to see Law Enforcement move so quickly. All i want is justice. Reporter gunn was killed, right here, literally just a few feet away from his home. This city remains divided. It was a group of Police Officers who came up with the money for officer smith to make bail. David . Steve osunsami in montgomery. Thanks, steve. Now, to new development in the urgent manhunt in houston on the. Several arrests, and this evening, they are still searching for more suspects after that dramatic Surveillance Video showing at least ten thiefs smashing into a gun store, stealing dozens of highpowered weapons. Three suspects now under arrest, but there are many more, and the question now . Where are the weapons . Houston. Reporter tonight, authorities in texas remain on the hunt for the brazen thieves seen here in this dramatic Surveillance Video, smashing into a houston gun store in less than 90 seconds. Using a chain tied to a pickup truck to yank the steel doors right off their hinges. Seven of the ten suspects who poured in and pillaged the store, still on the run tonight. Authorities making three arrests late wednesday, following a twoday manhunt. The thieves wasted no time using hammers to smash display cases. This one swiping 18 handguns in 30 seconds. Weve got people, right now, pounding the pavement, on the street, looking for those guns. Reporter in just under three minutes, the thieves got away with more than 50 firearms, including assault rifles. These guns can be used to commit more robberies or other sorts of criminal activity. They can be traded for drugs, for property, for other guns. They can be going to mexico. But none of its good. Reporter the feds say they were able to recover some of the but tonight, many of those guns, and several suspects, remain on the streets. David . Phillip mena in houston. Now, to a winter blast moving up the east coast over the next 24 hours. The clipper expected to impact the commute for millions tomorrow morning. Our weather team telling us alerts tonight in effect from kentucky to new jersey. And to the west there, a series of storms with snow, heavy rain and strong winds set to hit this weekend and into next week, were tracking it all for you. New developments tonight, the mystery crash that killed a billionaire ceo in oklahoma. Fiery wreckage now. Oil and gas executive Aubrey Mcclendons suv slamming into a highway overpass. Less than 24 hours after he was indicted. Tonight, there are new 911 calls from witnesses, and the question, was this an accident . Abcs Clayton Sandell on the case. Reporter this fiery crash, underpass, tonight is a mystery. I just heard a big bang and now theres smoke coming out reporter in this charred suv, the body of Energy Tycoon aubrey mcclendon. The cab is completely crushed. Oh my goodness, okay. What color . And theres fire and theres fire. Reporter cops say his speeding car veered left wednesday morning, straight into this wall. There was plenty of opportunity for him to correct or get back on the roadway, and that didnt occur. He went straight into the embankment. Reporter police dont know if the crash was an accident or intentional. But less than 24 hours earlier, mcclendon was indicted by a federal grand jury for allegedly conspired to fix prices for oil and gas leases. Many, many white collar criminals take their life during that time period, because they just cannot face the music. Reporter before he died, mcclendon said, i will fight to prove my innocence and to clear my name. He was married with three grown children and part owner of the oklahoma thunder basketball team. Tonight, without mcclendon, prosecutors say the charges will clayton, thank you. You we move on now to texas, and to a Flight Attendant accused of deliberately starting a fire while the passenger plane was in the air. The fbi now saying he confessed to igniting paper towels in a restroom during an American Airlines flight from dallas to detroit last month. He allegedly wanted to portray himself as a hero for putting out the fire. No one was injured. The Investigation Continues there. Now, to one of americas bestknown soccer stars making headlines tonight. Brandy chastain today saying she will donate her brain to Concussion Research and the disease cte. Of course, perhaps best remembered for that iconic image, celebrating team usa, winning the world cup, unbelievably, that was 1999. Abcs Kayna Whitworth on the mother and coach, and why she made this decision. Reporter tonight, the soccer star known for that celebration at the world cup coming forward about the dangers of the sport. 47yearold Brandi Chastain degenerative brain disease linked to concussions. Brandi is such an iconic figure for a big chunk of our country that hasnt really been focused on the concussion issue. Reporter as a college player, chastain did suffer from two concussions. Now a mom and soccer coach, shes concerned about the damage all those headers may have caused. She is having no symptoms. And shes living a normal life. But she is so well aware of what could be awaiting her. Reporter chastain telling usa today, but as you grow older, you sometimes say, gosh, am i losing my memory or did i used to forget when i went into a room what i went in there for . Adding, she hopes the research will protect younger players. Cte can only be diagnosed after death and has been found in nfl hall of famers and male soccer players, but so far never a female athlete. David . Kayna whitworth. Kayna, thank you. There is still much more this thursday. Hour for the escaped killer considered armed and dangerous. Schools today temporarily placed on lockdown. Families told to lock their doors. Well have late details from the scene. Also, the major debate tonight, and we want you to weigh in on this. The Popular High School teacher forced to resign. A student stealing a private photo from her phone, sharing it with other students. The School Firing the teacher for it. And later tonight, we couldnt believe it. The 11yearold golfer, watch this he is about to hit a hole in one. Unbelievable. Hes right here tonight. Your body was made for Better Things than rheumatoid arthritis. Before you and your rheumatologist move to a biologic, ask if xeljanz is right for you. Xeljanz is a small pill for adults with moderate to severe ra for whom methotrexate did not work well. Xeljanz can reduce joint pain and swelling in as little as two weeks, and help stop further joint damage. Including tuberculosis. Serious, sometimes fatal infections, lymphoma, and other cancers have happened. Dont start xeljanz if you have an infection. Tears in the stomach or intestines, low blood cell counts, and higher liver tests and cholesterol levels have happened. Your doctor should perform blood tests before you start and while taking xeljanz, and monitor certain liver tests. Tell your doctor if you were in a region where fungal infections are common, and if you have had tb, hepatitis b or c, or are prone to infections. Xeljanz can reduce the symptoms of ra, even without methotrexate. Ask your rheumatologist about xeljanz. Next tonight here, the teacher in South Carolina claiming she was forced to resign over a photo scandal. A student allegedly stealing a private picture from the teachers unlocked phone and sharing it with other students. The teacher now out of a job. And heres abcs linzie janis. Reporter tonight, a South Carolina teacher is fighting back. I havent done anything reporter after one of her students stole private, seminude photos from her cell phone, sharing them on social media. It makes you just want to just ball up and just stay there. Reporter Leigh Anne Arthur says instead of punishing the student, the School District forced her to resign. You know, you dont think about somebody invading your privacy like that. Reporter the School District explanning its decision, saying, this is a case where a staff member, properly supervising students, could have prevented a serious problem. But she says she was in the hallway greeting students when the 16yearold boy snooped into the unlocked phone on her desk, taking pir sures s pictures of her intimate images, even taunting her. Turned around and said, your day of reckoning is coming. Reporter she says the sex ya selfies were meant to be a valentines day surprise for her husband. David, many of arthurs students are coming to her defense, gathering thousands of signatures in an online petition student broke any laws. David . Linzie janis. Linzie, thank you. When we come back here, the new Health Headline tonight. The mysterious bacteria. 18 dead in the heartland. The cdc investigating tonight. Also, the escaped murder suspect on the loose. The manhunt under way tonight. Schools on lockdown today. And later here, the first look. Kristin wig, Melissa Mccarthy. These are the new ghostbusters. And the clues tonight. Everybody talking about it on social media tonight. T more fiber. Flax seeds. Yogurt. Get moving. Keep moving. I know try laxatives. Been there, done that. My chronic constipation keeps coming back. I know. Tell me something i dont know. Vo linzess works differently from laxatives. Linzess treats adults with ibs with constipation or chronic constipation. It can help relieve your belly pain, and lets you have more frequent and complete bowel movements that are easier to pass. Do not give linzess to children under six and it should not be given to children six to seventeen. Dont take linzess if you have a bowel blockage. Get immediate help if you develop unusual or severe stomach pain, especially with bloody or black stools. 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