Transcript for Sen. Elizabeth Warren touts female political success at Iowa debate
We'll begin with the showdown for Democrats last night. The final debate before the first votes are cast in the Iowa caucuses less than three weeks away and tension between Bernie Sanders and Elizabeth Warren took center stage during the debate and in a revealing moment right after. Linsey Davis starts us off with all the latest. Good morning, linsey. Reporter: Good morning, George. Six candidates, smallest debate stage yet and the least diverse. As for senators Elizabeth Warren and Bernie Sanders, they came united on at least one front, they did not want to fight each other, in fact, their most confrontational moment happened after the debate was over when they deliberately did not shake hands. In the last debate before the first votes are cast in Iowa, a reluctant face-off between the two Progressive senators on stage. Bernie is my friend and I am not here to try to fight with Bernie. Reporter: Bernie Sanders continuing to outright deny claims he told Elizabeth Warren during a private conversation in 2018 that a woman could not win the election. Well, as a matter of a fact I didn't say it and I don't want to waste a lot of time on this because this is what Donald Trump, maybe some of the media want. Anybody knows me knows that it's incomprehensible that I would think that a woman could not be president of the United States. Reporter: But Warren insists it happened and that the women on the stage are in better position to take on president trump. So can a woman beat Donald Trump? Look at the men on this stage. Collectively they have lost ten elections. The only people on this stage who have won every single election that they've been in are the women. Amy and me. So true. So true. Reporter: And in what could be a sign of simmering tensions, Warren pulled back from a handshake following the debate, abruptly ending the exchange. Last night's debate was also the first since president trump ordered a strike against the top Iranian general pushing foreign policy front and center. Sanders and former vice president Biden battling it out over the origin of the Iraq war. I not only voted against the war I helped lead the effort against that war. I said 13 years ago it was a mistake to give the president the authority to go to war. Reporter: But others like veteran Pete buttigieg looking to the challenges of the future. I bring a different perspective. There are enlisted people that I served with barely old enough to remember those votes on the authorization after 9/11 on the war in Iraq. The next president is going to be confronted with national security challenges different in scope and in kind. From anything we've seen before. Donald Trump is taking us toward another war. We have a situation where he got us out of the Iranian nuclear agreement, something I worked on for a significant period of time. As president I will get us back into that agreement. Reporter: As impeachment grips Washington, former vice president Joe Biden insists it won't be a distraction if he becomes the nominee. It doesn't really matter whether or not he's going to -- I got to be in a position that I think I can't hold a grudge. I have to not only fight but heal and as president of the United States that's what I will attempt to do. Reporter: The stakes are especially high for the three senators on the stage last night as they're going to basically have to come off the campaign trail in order to attend that impeachment trial in D.C. For potentially the next few weeks, for six days a week. That will go through Iowa, maybe even New Hampshire. Thanks very much.
This transcript has been automatically generated and may not be 100% accurate.