about the republican race. outside of texas, donald trump seems poised to score some very big wins in contest despite some conflicting and curious answers to a question that's left him exposed over very sensitive racial ground. nbc's katy tur starts our coverage tonight. >> reporter: tensions high in radford, virginia. secret service body slamming a "time" photographer who tried to leave the campaign mandated press pen. trump on edge, too. this morning blaming his refusal to condition dem the kkk and david duke in a cnn interview on a bad ear piece. >> i'm sitting in a house in florida with a very bad earpiece that they gave me, and you could hardly here what he was saying. >> reporter: a complaint he did not make during that interview. >> i don't know anything about david duke, okay. i don't know anything about what you're even talking about with white supremacy or white supremacists, so i don't know. >> reporter: trump disavowed the cline's infamous former leader last week. david duke and robo calls, white supremicist movement supporting you. any words for that? >> i disavow it and

>>> tonight the klan controversy exploding around donald trump after refusing to condemn the kkk's former leader. what he's saying now and what we found him saying years ago. >>> plus, tensions boil over at trump's rally, and tonight some republican leaders a a scrambling to stop him. >>> school shooting emergency. all-out chaos as police say a 14-year-old suddenly opened fire in the cafeteria. >>> taking the stand, an emotional erin andrews tells the jury about her hotel nightmare as a stalker secretly taped her and posted the video for the world to see. >>> craving sleep. a wake-up call tonight for millions struggling to lose weight and trying to get more rest. >>> and hollywood rocked as controversy takes center stage at the oscars. "nightly news" begins right now. >> announcer: from nbc news world headquarters in new york, this is ennightly news with le\ter holt. >>> good evening. from our election eve of super tuesday, one of the biggest days yet in the presidential contest, in an election season filled with lead-shaking moments, spray tans. the kkk and ear piece malfunctions

>>> a rock star reception for donald trump. >> wow, wow, this is amazing. >> commanding a massive crowd in alabama. facing fire from all sides after failing to condemn the kkk. >> not only is that wrong, it makes him unelectable. >> but can anything stop the front-runner's surge on the campaign's biggest day yet? and is hillary clinton on the verge of locking down the nomination? >>> and we are taking you behind the scenes of hollywood's biggest night like only "gma" can from the red carpet to backstage. you won an oscar, brie. you won an oscar. >> i really can't believe it. >> we're one-on-one exclusively with the big winners. their first interview, seconds after taking home the gold. all the unforgettable moments. >> let's get this money. >> the "gma" oscars after-party starts right now. >> good morning. >> america. go crazy crazy cake by the ocean [ cheers and applause ] >>> can we take you home with us? we love to walk out every morning with you here with us. >> good morning. >> good morning, america. good morning from hollywood. [ cheers and applause ] >> we have a very speci

tuesday contest. this he'll cast their ballots. could make hillary clinton and donald trump unstoppable. also have a brand-new poll out his biggest lead yet at nearly 50% across the country. good morning. >> reporter: good morning to you as we just saw polls show donald trump may have a big night tomorrow but now he's dealing with a problem involving the kkk and the other candidates are all seizing on it. >> wow. >> wow, this is amazing. >> reporter: overnight, donald trump speaking to a massive crowd in alabama, a super tuesday state, but not mentioning a syllable about the controversy involving the ku klux klan and their former grand wizard david duke. >> wow say you condemn them and don't want their support? >> well, i have to look at the group. i mean i don't know what group you're talking about. >> i'm just talking about david duke and the ku klux klan here. >> i don't know -- i don't know david duke. i don't believe i've ever met him i'm pretty sure i never met him. >> we cannot be a party that nominates someone who refuses to condemn white supremacists and the ku klux

that brought everyone to their feet. reception for donald trump. >> wow, wow, this is amazing. >> commanding a massive crowd in failing to condemn the kkk. >> not only is that wrong, it makes him unelectable. >> but can anything stop the surge on the campaign's biggest day yet? and is hillary clinton on the verge of locking down the nomination? >>> and we are taking scenes of hollywood's biggest night like only "gma" can from the red carpet to on an oscar, brie. you won an oscar. >> i really can't believe it. >> we're one-on-one exclusively with the big winners. their first after taking home the gold. all the unforgettable moments. >> let's get this money.ars after-party starts right now. >> good morning. >> good morning. go crazy crazy [ cheers and applause ] >>> can we take you home with us? we love to walk out eith you here with us. >> good morning, america. good morning from hollywood. [ cheers and applause ] >> we have a very special show coming up this morning. from the legendary el capitan theater here in l.a. and just like the oscars, we as you can see we have a live,

he stop her? >> thank you, david. >>> meanwhile, on the republican side of this race, donald trump out on the trail and opening fire on his new nemesis, marco rubio. trump is getting help now from his new ally, chris christie. but rubio who had been keeping it positive, until recently, is not relenting. mary bruce is in memphis, tennessee, this morning. mary, good morning to you. >> reporter: hi, dan, good morning. with super tuesday around the corner, the attacks are getting supersized. it is getting ugly out here. the republican candidates seem to be using every chance they get to take each other down. >> he's a very nasty guy. >> friends don't let friends vote for con artists. >> this is my country, damn it! my country! >> reporter: this morning, the top republican candidates are eviscerating each other. unleashing some of the nastiest attacks yet. as they head into super tuesday. >> but he's flying around on hair force one. >> reporter: marco rubio trying to out-trump trump has launched a personal assault against the front-runner. >> he just came out firing. >> reporter: rubio'

candidate's bombshell endorsement, a former foe signing on. >> there is no better fighter than donald trump. >> now double-teaming marco rubio. >> he was putting on makeup with a trowel. >> rubio, meanwhile, taking his own swipes. >> he was having a meltdown. >> the latest twists and turns and the predictions for today's democratic primary in south carolina as we head into a crucial super tuesday. >>> zika alert. the cdc's startling report. the american pregnant women who visited countries with zika outbreaks. what happened? plus, the new travel advice from health officials. our dr. besser tells you what you need to know. >>> opening up, the superstar jennifer garner talking for the with ben affleck. her really candid comments about her ex. did ben's alleged affair with the nanny truly end their marriage? >>> and countdown to the oscars. your backstage pass to the glitz, glamour and huge surprises. >> right now the red carpet is covered in plastic, but that will soon change. >> the big reveals from the producers, presenters going animated, excitement bubbling over as hollywood gears up for

. donald probably needs a lifeline after last night and he called in chris christie. i respect that. fair share of endorsements. >> reporter: this morning in dallas rubio had ripped into the front-runner. >> what we are dealing with here, my friends, is a con artist. >> reporter: mocking a series of trump's misspelled tweets. >> and i only reached two conclusions. number one, that's how they spell those words at the wharton school of business where he went or, number two, just like trump tower he must have hired a foreign worker to do his own tweets. he called me mr. meltdown. let me tell you something. last night during the debate during one of the breaks, two of the breaks. he went backstage, he was having a meltdown. first, he had this little makeup thing applying like makeup around miss mustache, had one of those sweat mustaches and then wanted a full length mirror, maybe to make sure his pants weren't wet, i don't know. >> reporter: rubio's all-out assault coming after last night's republican debate in hues top. he berated trump for his hiring practice. >> if he built the wall

, new york. >>> still ahead tonight, millions saw donald trump accused in last night's debate of exploiting undocumented workers at the site of his trump tower. what really happened? tonight the results of investigation into that. just seeing things. that's a unicorn, sort of. and she led police on a wild chase that's >>> now to that controversy that has roared back into the headlines about donald trump and one of the most famous properties that bears his name, trump tower. trump, who vows to deport all undocumented immigrants, was accused in last night's debate of using undocumented labor himself at the site of trump tower. nbc news has investigated what went on there for months now, and tonight nbc news senior investigative correspondent isn'tiaia mcfadden reveals what we found. >> reporter: last night marco rubio let loose on donald trump. >> you lied about the polish workers. >> yeah, yeah, yeah. >> that was 38 years ago. statute of limitations on lies. >> reporter: in the 1980s undocumented immigrants did do much of the initial work on empire in new york, trump tower, which

donald trump on the debate stage, a rejuvenated marco rubio struck again today and then donald trump struck back with a surprise announcement of new jersey governor chris christie. it was all part of a nasty back and forth war of words between trump and rubio on the trail just four days before super tuesday. nbc's katy tur starts off our coverage. katy, what a day. >> reporter: lester, they say everything is bigger in texas, and this endorsement certainly came as a big surprise. less than a month after he dropped out and just four days to go until super tuesday, chris christie is getting behind donald trump and trying to lay waste to marco rubio. >> ladies and gentlemen, it is my to introduce the next president of the united states, donald trump! >> reporter: donald trump added a little jersey pride to his texas swagger in fort worth today. former presidential candidate chris christie officially endorsing the front-runner. >> and i really was happy with this one right here. so, chris, thank you. we love you, man. >> it's all make-believe. >> reporter: less than a month ago chri