
Elizabeth Warren refused to shake Bernie Sanders' hand at the conclusion of Tuesday night's primary debate, a tart ending after the two contenders handled the growing tensions between their campaigns gracefully during the evening.

Warren approached Sanders on the debate stage after it ended. He held his hand out to her. She appeared to start to reach out but whipped her hand back and he withdrew his.

The two then spoke for about 10 seconds while Tom Steyer stood between them.

Elizabeth Warren refused to shake Bernie Sanders hand at the end of debate

Bernie Sanders had reached out his hand to her but Elizabeth Warren pulled hers back

Tom Steyer said he didn't know what Warren and Sanders discussed

It was unclear what they talked about and Steyer told CNN he didn't know.

'I was just going up to say good night. And I felt like okay, there's something going on. Good night! I'm out of here! I really wasn't listening,' he said.

'How can you not hear Bernie Sanders?' Anderson Cooper asked.

'They were talking about getting together or something. I really didn't listen,' Steyer said.

'It was one of those awkward moments where I felt like, you know, I need to move on as fast as possible. You could see it was an awkward moment. My goal was simply to say good night to two people I respect.

'The last thing I wanted to do was get in between the two of them and try and listen in. That was not my goal and I didn't do it.'

Fireworks had been expected between the two senators after an increasingly bitter feud erupted ahead of Tuesday night's debate, the first of 2020 and last gathering of Democratic candidates before voters go to the caucuses in Iowa.

Instead, the pair calmly addressed a report that Sanders told Warren in a private 2018 meeting at her Washington D.C. apartment that a female candidate couldn't beat Donald Trump and she used the line of questioning to get in a shot at her male rivals on stage.

Sanders said he'd never told Warren a woman can't win.

'As a matter of fact, I didn't say that. And I don't want to waste a lot of time on this because this is what Donald Trump, maybe some of the media would want. Anybody who knows me knows it is incomprehensible that I would think that a woman could not be president of the United States,' the Vermont senator said.

'Hillary Clinton won the popular vote by three million votes. How could anybody in a million years think a woman could become president of the United States? And let me be very clear, if any of the women on this stage, or any of the men on this stage, win the nomination - I hope that's not the case, I hope it's me - but if they do, I will do everything in my power to ensure they are elected in order to defeat the most president in the history of our country,' he added to applause from the audience.

Six Democratic presidential contenders took the stage at Drake University in Des Moines, Iowa, on Tuesday night. Pictured left to right: Tom Steyer, Elizabeth Warren, Joe Biden, Bernie Sanders, Pete Buttigieg and Amy Klobuchar

Elizabeth Warren slammed a claim women can't be president and got in a shot at her male rivals at Tuesday's Democratic debate as Bernie Sanders denied telling her a female candidate couldn't beat Donald Trump

The first debate of 2020 took a sharp turn after Sanders was asked about a report he told Warren in a private meeting that a woman couldn't win the White House

CNN's Abby Phillips, one of the debate moderators, asked again: 'Senator Sanders, I do want to be clear here, you're saying that you never told senator Warren that a woman could not win the election?'

'That is correct,' he responded.

But Phillip then turned to Warren and asked: 'Senator Warren, what did you think when Senator Sanders told you a woman could not win the election?'

The audience laughed at the question.

'I disagreed,' Warren replied. 'Bernie is my friend, and I am not here to try to fight with Bernie. But, look, this question about whether or not a woman can be president has been raised and it's time for us to attack it head-on.'

She then went on to attack the record of the men on stage – Sanders, Joe Biden, Pete Buttigieg, and Tom Steyer – while praising her and Amy Klobuchar's record as political candidates.

'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,' she said.

'So true,' Klobuchar chimed in.

Warren continued: 'And the only person on this stage who has beaten an incumbent Republican anytime in the past 30 years is me. And here's what I know. The real danger that we face as Democrats is picking a candidate who can't pull our party together or someone who takes for granted big parts of the democratic constituency. We need a candidate who will excite all parts of the Democratic Party, bring everyone in, and give everyone a Democrat to believe in. That's my plan and that is why I'm going to win.'

Klobuchar also pushed back at concerns that a woman can't beat President Trump

Klobuchar also pushed back at concerns that a woman can't beat President Trump.

'I point out that you don't have to be the tallest person in the world. James Madison was 5'4'. You don't have to be the skinniest person in the room. You don't have to be the loudest person. You have to be competent,' she said. 'And when you look at what I have done, I have won every race, every place, every time. I have won in the reddest of districts. I have won in the suburban areas, in the rural areas. I have brought people with me.'

Sanders then pointed out he does have a win against a Republican: in 1990.

HOW LONG EACH CANDIDATE SPOKE Elizabeth Warren - 19 minutes, 11 seconds Bernie Sanders - 18 minutes, 26 seconds Amy Klobuchar - 16 minutes, 59 seconds Pete Buttigieg - 16 minutes, 48 seconds Joe Biden - 16 minutes, 17 seconds Tom Steyer - 12 minutes, 24 seconds Source: NBC News Advertisement

'Well, just to set the record straight, I defeated an incumbent Republican running for Congress,' he said.

'When?' Warren inquired.

'1990,' he said.

'30 years ago,' she noted. 'And I said, I was the only one who's beaten an incumbent Republican in 30 years.'

Biden then piped in that he agreed a woman can win the White House. And he made a pitch for votes based on his appeal to African American voters, a group he gets a lot of support from.

'I agree women can win. I have campaigned for 27 of them in 2018. The best group I have campaigned for. The real issue is who can bring the party together and represent all elements of the party. African-American, brown, black, women, men. Gay, straight. The fact of the matter is in terms of endorsement around the country, where ever we go, I am the one who has the broadest coalition of anyone running up here,' the former vice president said.

Also defending Sanders Tuesday night was President Trump, who addressed the controversy at his campaign rally in Milwaukee that was taking place during the Democratic debate.

'According to her he said this,' he said of Warren's claim that Sanders said a woman can't beat him. 'And I don't believe that he said this. Because, I don't know him, I don't particularly like him, he's a nasty guy, but I don't believe he said it. It's not his deal.'

He went on to add: 'I don't believe that Bernie said that. I really don't. So, you know, Bernie, it's not the kind of a thing he'd say.'

After the debate was over, Sanders adviser Jeff Weaver once again denied that Sanders told Warren a woman couldn’t win the White House.

'He says he did not say that. It's inconceivable that he would say that because he doesn't believe it,' he said.

'They had a long conversation about the challenges of women running in the year of Trump for sure. Because she asked him do you think a woman can run. She brought it up,' he said.

Asked by DailyMail.com whether Sanders agreed with Warren's premise that it would be a challenge for a woman to win, Weaver said: 'That there are challenges to running against somebody like Trump if you're a woman. Of course there are challenges. Of course. They will do and say anything in that White House. You'd be living in an another alternative universe if you didn't believe that that's true.'

'Does that mean you can't win?' he continued. 'Of course it does not mean you can't win. You saw tonight at the end. Every candidate up there was asked about some particular challenge they had as perceived by the moderator. Every candidate has challenges.'

He said Sanders did not urge Warren not to run for president. 'No, she had told him that she was running,' said Weaver, who wasn't there but is a senior adviser to Sanders. 'He did not say a woman cannot run [win] running against Trump. Hillary Clinton had just gotten 3 million more votes than Trump. Doesn't make sense.'

Vice President Joe Biden proclaimed that he's taken the most heat from President Trump and the Republicans - and his poll numbers are only going up

Joe Biden reminded the debate audience that President Trump (pictured) and Republicans had 'savaged' his surviving son, who's become a central character in the president's impeachment

The Sanders and Warren brawl didn't produce the anticipated sparks nor did a bit of bickering among the contenders on health care policy.

The liberals on the stage – Warren and Sanders – support a Medicare for all single-payer system while moderates like Biden, Buttigieg and Klobuchar favor expanded Obamacare.

Buttigieg pushed back against criticism from Warren that his plan is too small.

'It's just not true,' he said. 'We have to move past Washington mentality that suggests that the bigness of plans only consistent of how many trillions of dollars they put through the treasury.'

Warren hit back.

'The numbers that the mayor is offering don't add up,' the Massachusetts senator said. 'The average family in America last year paid $12,000 in some combination of deductible and copay and uncovered expenses and fees. You can't cover that with a kind of money that the mayor is talking about.'

Biden used the occasion to tout Obamacare, a plan passed when he was vice president and Barack Obama was in the White House.

'I would argue that the biggest breakthrough in recent time was us being able to do an administration with five democratic presidents couldn't get done. That is pass Obamacare,' he said.

There were a few break out moments in what was an otherwise low-key debate.

Steyer attacked Buttigieg for his work at the elite consulting firm McKinsey.

'Look, Mayor Pete has three years as an analyst in McKinsey,' he said. 'I have 30 years of international business experience. I can beat Trump on the economy. We're going to have to beat him on the economy and I look forward to taking him down in the fall on the debate stage.'

Buttigieg responded: 'Demoted me. I thought I was an associate. That's okay. It was not the biggest part of my record.'

And Biden was asked if he was ready to take on Trump, given the president's propensity to attack and his slams against Biden's son Hunter.

'I've been the object of his affection now more than anybody else on the stage. I've taken all the hits he can deliver, and I'm getting better in the polls,' the former vice president responded.

'This Republican Party, they've gone after - savaged my surviving son, gone after me, told lies that your networks and others won't even carry on television because they're flat-out lies,' Biden noted. 'And I did my job, the question is whether he did his job. And he hasn't done his job.'

The night began with the candidates aiming their fire at Trump.

Sanders and Biden accused President Trump of lying about his reasons for taking out Iranian General Qassem Soleimani

Klobuchar and Warren both expressed a need to remove U.S. troops from the Middle East. Klobuchar said: 'I have long wanted to bring our troops home. I would do that.' Warren added: 'We should stop asking our military to solve problems that cannot be solved militarily'

Pete Buttigieg accused Trump of committing more troops to the Middle East after vowing to take America out of endless wars

Sanders and Biden accused the president of lying about his reasons for taking out Iranian General Qassem Soleimani and the candidates were in agreement American troops need to come home from the Middle East.

The first shots were fired at Trump, who was holding a campaign rally in Milwaukee as they were on stage.

Sanders kicked off the attacks on the president when the candidates were asked about their own qualifications to be commander in chief.

'What we have to face as a nation is that the two great foreign policy disasters of our lifetimes, with the war in Vietnam and the war in Iraq. Both of those wars were based on lies. And right now, what I fear very much is we have a president who is lying again and could drag us into a war that is even worse than the war in Iraq,' the Vermont senator said.

Trump defended his order to take out Soleimani during his rally in Milwaukee (pictured)

Biden agreed that Trump lied, accusing the president of making up a threat against four U.S. embassies as his reason for taking out Soleimani, a move that ratcheted up tensions in the Middle East and resulted in a retaliatory attack from Iran on U.S. targets in Iraq.

'Quite frankly, I think he's flat-out lied about saying that the reason he went after – the reason he made the strike was because our embassies were about to be bombed,' the former vice president said.

The candidates were generally in agreement U.S. troops should be with drawn from the Middle East.

'I would leave some troops there, but not in the level that Donald Trump is taking us right now. Afghanistan, I have long wanted to bring our troops home. I would do that. Some would remain for counterterrorism and training,' Klobuchar said.

Warren agreed.

'I think we need to get our combat troops out. You know, we have to stop this mind-set that we can do everything with combat troops. Our military is the finest military on Earth. And they will take any sacrifice we ask them to take. But we should stop asking our military to solve problems that cannot be solved militarily. Our keeping combat troops there is not helping,' she said.

Buttigieg accused Trump of committing more troops to the Middle East after making a vow to take America out of endless wars.

'We can continue to remain engaged without having an endless commitment of ground troops. But what's going on right now is the president's actually sending more. The very president who said he was going to end endless war, who pretended to have been against the war in Iraq all along, although we know that's not true, now has more troops going to the Middle East,' the former South Bend mayor said.

The president defended his order to take out Soleimani during his rally.

'They're saying, 'Was the attack imminent? Was it imminent?' Does the fact that he's killed hundreds of thousands of people and thousands of Americans, and horribly killed and wounded thousands and thousands, that doesn't matter,' Trump said at his second campaign rally of 2020.

''Was the attack imminent?' I think they're going to start a new investigation: 'Was the attack on this horror?'—and by the way, he was in a country he wasn't allowed to be in. We don't mention that,' Trump continued.

Warren and Sanders are seen greeting each other on the stage. Tensions between the two senators were high heading into the debate after Warren confirmed a report claiming Sanders told her a woman couldn't win against President Trump

Democrats, meanwhile, were having the smallest debate field to date. Only six candidates made the qualifications to be on the stage of the first debate of 2020.

And all the candidates are white. Andrew Yang, who made the Los Angeles stage, didn't hit the polling requirements for Tuesday night, despite his appeals to the Democratic National Committee to commission more polls over the holiday season to give him a fighting chance.

Tuesday's debate was the last one before voters head to the polls. The Iowa caucuses, the first contest in the Democratic nomination process, are on February 3.

There are three more debates on the calendar – ahead of the New Hampshire primary, the Nevada primary and the South Carolina contest.

There was a light-hearted moment of teasing between Biden and Sanders when the former vice president joked he wouldn't meet with North Korea's Kim Jong Un because of a threat he made against him.

'Absent pre-condition, I would not meet with the quote-supreme leader who said Joe Biden is a rabid dog, he should be beaten to death with a stick,' Biden said.

'Other than that you like him,' Sanders injected as the audience laughed.

'And he got a love letter from Trump right after that,' Biden responded.

The first 45 minutes of the debate focused on the candidates' qualifications for president, foreign policy issues, trade agreements, and climate change.

Sanders got in a knock about Trump's ability to negotiate a deal.

'The answer is we can do much better than a Trump-led trade deal,' he said when asked about the China trade deal the president is scheduled to sign on Wednesday.

'This deal, and I think the proponents of it acknowledge, will result in the continuation of the loss of hundreds of thousands of good-paying jobs as a result of outsourcing. The heart and soul of our disaster trade agreements.'

Warren agreed with him.

'We have farmers here in Iowa who are hurting. And they are hurting because of Donald Trump's initiated trade wars. We have workers who are hurting because the agreements that have already been cut really don't have enforcement on workers' rights. This new trade deal is a modest improvement. Senator Sanders himself has said so. It will give some relief to our farmers, it will give some relief to our workers. I believe we accept that relief, we try to help the people who need help, and we get up the next day and fight for a better trade deal,' she said.