Surging front-runner Bernie Sanders came under fire early in the Democratic debate in South Carolina as rival Michael Bloomberg said Russia was helping the senator because it knew he would lose in November to Republican President Donald Trump.

REUTERS/Jonathan Ernst 

Mike Bloomberg going after Bernie Sanders: "Vladimir Putin thinks that Donald Trump should be president of the United States and that's why Russia is helping you get elected so you lose to him." REUTERS/Jonathan Ernst 

Bernie Sanders replying to Mike Bloomberg's allegation that Russia is helping the Vermont senator's campaign: "Hey Mr. Putin, if I'm president of the United States you're not going to interfere in any more American elections." REUTERS/Jonathan Ernst 

Pete Buttigieg criticized Bernie Sanders for what he said are shifting costs of his ambitious plans. "I can tell you exactly how it all adds up. It adds up to four more years of Donald Trump, Kevin McCarthy as Speaker of the house, and the inability to get the senate into Democratic hands. The time has come to stop acting like the presidency is the only thing that matters. Not only is this a way to get Donald Trump reelected, we got a house to worry about, we got a senate to worry about. This is really important. If you want to keep the house in Democratic hands, you might want to check with the people that actually turned the house blue: Forty Democrats, who are not running on your platform, they are running away from it as fast as they possibly can." REUTERS/Jonathan Ernst 

Tom Steyer: "We are looking at a party that has decided that we're either going to support someone who is a Democratic Socialist or somebody who has a long history of being a Republican.... I am scared, if we cannot pull this party together, if we go to one of those extremes, we take a terrible risk of reelection Donald Trump." "That is a risk that will hurt the American people in a way that we, none of us on this stage, should be willing to risk." REUTERS/Jonathan Ernst 

Joe Biden pointed out Sanders' voting against the 1993 Brady Bill that imposed mandatory background checks and waiting periods for gun purchases. "Bernie voted five times against the Brady bill ... and wanted a waiting period of 12 hours," Biden said. Referring to the 2015 mass shooting at a church near the debate venue, Biden added: "I'm not saying (Sanders is) responsible for the nine deaths, but that man would not have been able to get that weapon with the waiting period." REUTERS/Jonathan Ernst 

Elizabeth Warren a progressive ally of Bernie Sanders, took a swing at her old friend.

"I think I would make a better president than Bernie. And the reason for that is that getting a progressive agenda enacted is going to be really hard," she said. "I dug in, I did the work, and then Bernie's team trashed me." REUTERS/Jonathan Ernst 

Michael Bloomberg: "Bernie will lose to Donald Trump, and Donald Trump and the House and the Senate and some of the statehouses will all go red and then between gerrymandering and appointing judges, for the next 20 or 30 years we are going to live with this catastrophe." REUTERS/Jonathan Ernst 

Amy Klobuchar addresses coronavirus after suggesting Americans check the CDC website for guidance: "What would I do? I would better coordinate throughout my presidency to be ready for the next pandemic and to prepare for this one." REUTERS/Jonathan Ernst 

Bernie Sanders hit back against the attacks on his electability, noting that opinion poll after opinion poll showed him being able to beat Trump nationally.

"And if you want to beat Trump, what you're going to need is an unprecedented grassroots movement of black and white and Latino, Native American and Asian, people who are standing up and fighting for justice. That's what our movement is about." REUTERS/Jonathan Ernst 

On the African-American vote he has been hoping will score him a win in South Carolina's primary on Saturday, Biden said: "I've worked like the devil to earn the vote of the African-American community, not just here but across the country." "The people know me. My entire career has been wrapped up in dealing with civil rights and civil liberties. I don't expect anything. I plan to earn the vote. I'm here to ask. I'm here to earn it. But, folks, I intend to win in South Carolina, and I will win the African-American vote here in South Carolina." REUTERS/Jonathan Ernst 

Warren reprised her criticism from the last debate of former New York Mayor Michael Bloomberg, a billionaire who has poured more than $500 million into his campaign.

"I don't care how much money Mayor Bloomberg has. The core of the Democratic Party will never trust him. He has not earned their trust. I will. And the fact that he cannot earn the trust of the core of the Democratic Party means he is the riskiest candidate standing on this stage." REUTERS/Jonathan Ernst 

Pete Buttigieg criticized Sanders for the shifting estimates on the costs of his proposals such as government-run healthcare. "I can tell you exactly how it all adds up. It adds up to four more years of Donald Trump," Buttigieg said. "Not only is this a way to get Donald Trump re-elected, we got a House to worry about, we got a Senate to worry about." REUTERS/Jonathan Ernst 

Bernie Sanders and Joe Biden talk at the tenth Democratic 2020 presidential debate at the Gaillard Center in Charleston, South Carolina, February 25. REUTERS/Jonathan Ernst 

Pete Buttigieg draws cheers and boos after saying Bernie Sanders has "nostalgia for the revolutionary politics of the 1960s," adding Democrats are "not going to win by reliving the Cold War." REUTERS/Elizabeth Frantz 

Joe Biden crosses his arms during a commercial break. REUTERS/Jonathan Ernst 

Elizabeth Warren, Bernie Sanders, and Joe Biden debate. REUTERS/Jonathan Ernst 

Bernie Sanders listens to Joe Biden talk. REUTERS/Jonathan Ernst 

Mike Bloomberg, Bernie Sanders and Joe Biden listen as Pete Buttigieg and Elizabeth Warren discuss an issue. REUTERS/Jonathan Ernst 

Bernie Sanders and Joe Biden talk. REUTERS/Jonathan Ernst 

Bernie Sanders walks on stage during a break. REUTERS/Jonathan Ernst