Transcript for Tense words between Sanders, Warren during debate
And now to the race for 2020 last night. If you watched the debate last night until the very end, you noticed Elizabeth Warren refusing to shake Bernie Sanders' hand, after the exchange during the debate over whether a woman could win in 2020. ABC's linsey Davis is just back from Iowa. Reporter: They call each other friends, but when Bernie Sanders extended his hand to Elizabeth Warren on the Iowa debate stage, she refused to shake it. The two then appearing to exchange tense words. A rift between the two Progressives appeared after Warren claimed that in a private 2018 conversation, Sanders told her that a woman can't win the white house. Well, as a matter of fact, I didn't say it. Hillary Clinton won the popular vote by 3 million votes. How could anybody in a million years not believe that a woman could become president of the United States? Reporter: Warren not backing down. I think the best way to talk about who can win is by looking at people's winning record. 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: Many of us saw that tension right after the debate. Sanders' campaign manager said that Warren came to raise a concern and he said, let's talk about that later. Tom Steyer, of course, ended up in the middle of that exchange. He says he was trying to get out of the way as fast as possible, David. Probably smart. Linsey, thank you.
This transcript has been automatically generated and may not be 100% accurate.