“If Bernie ends up being one of these frontrunners, he’ll have to moderate. I’m not going socialist. Never been a socialist,” Sen. Joe Manchin (D-W.Va.) said. “If he doesn’t change, I’ve got a dilemma there. We’ll see. But we’re talking about hypotheticals. I think there’s going to be a lot happening between now and then.”

The soul-searching within the establishment wing of the Democratic Party comes after Sanders solidified his frontrunner status in Iowa and New Hampshire, which produced a pair of cringeworthy finishes for Biden. The former vice president did so poorly in New Hampshire that he ditched his own election night watch party to head to South Carolina, possibly giving an opening to Bloomberg, who skipped the first four contests.

“I’m feeling a momentum shift to Bloomberg right now,” said Rep. Lou Correa (D-Calif.), who endorsed Biden in the summer and plans to stick with him.

One of the most glaring examples of the change in tide on Capitol Hill is a trio of Bloomberg endorsements from the Congressional Black Caucus on Wednesday — a not-so-subtle show of force against Biden, who remains the favored candidate among black voters nationally.

For months, many members of the CBC had either publicly or privately backed Biden, declining to endorse two of their fellow members running for president, Sens. Kamala Harris and Cory Booker, out of respect for the former vice president. And senior members of the CBC were the most vocal defenders of Biden last summer when he became embroiled in controversy over his comments about working with segregationists.

Rep. Gregory Meeks (D-N.Y.), a senior member of the CBC who endorsed Bloomberg on Wednesday, declined to say whether he thinks Sanders could beat Trump and added he would fully support the eventual nominee. But Meeks — who fought Bloomberg over his stop-and-frisk policies as mayor — said the trajectory of the race is what persuaded him to weigh in now.

“There’s a number of [candidates] who are ideologically where I am. But I also had to add to that electability,” Meeks said. “And that’s a tremendous consideration we’ll have to make because you can have the best ideology but if you’re not electable, then where are we? We’ve got to win.”

When asked whether Biden’s faltering was a factor, Meeks didn’t deny it: “To say that it was zero factor would not be the truth,” he said. “It was one of many factors because you’ve got to be able to pull it together, you’ve got to make sure that one has the ability to win.”

Several other CBC members said privately that they expected other black lawmakers who previously supported Biden to soon come out for Bloomberg.

But there are some concerns that Bloomberg, who has poured hundreds of millions of dollars into the race so far, remains untested heading into Super Tuesday on March 3: He hasn’t gone head-to-head at a single debate this cycle, though he is expected to qualify for Nevada next week.

Some Democrats also fear a potential drip-drip of controversies, like a 2015 audio tape that surfaced this week on which Bloomberg defends his stop-and-frisk policies in language that have prompted accusations of racism.

For many Democrats, there is a real fear about Biden’s staying power, especially if Senate Republicans make good on their threat to investigate Hunter Biden’s role at a Ukrainian gas company now that Trump’s impeachment trial is over.

“Is the Senate going to bring in Hunter Biden?” Correa said, sighing. “That’s tough, the politics are tough.”

Two self-described moderate Democrats did finish strong in Iowa and New Hampshire, led by former South Bend, Ind., Mayor Pete Buttigieg. But Democrats said privately they’re desperate for a candidate with the cash and name recognition to beat Trump — something they don’t know if Buttigieg or Minnesota Sen. Amy Klobuchar, who finished a strong third in New Hampshire, can deliver — without exposing them to ceaseless GOP attacks on socialism.

"There's a lot of people right now on the fence," said Rep. Dean Phillips (D-Minn.), a prominent supporter of Klobuchar. Asked about Klobuchar's surge, Phillips said: "She is being elevated in more and more conversations every day. That said, so is Michael Bloomberg."

The most intense fears are among the 30 Democrats sitting in districts that Trump won in 2016, who fear they can’t compete in 2020 if Sanders becomes the nominee and spurs months of “Medicare for All” attacks from GOP groups in their districts.

Some of the most endangered incumbents, like Rep. Anthony Brindisi of New York, have acknowledged they wouldn’t be able to support Sanders if he does become the nominee, hoping at best that voters split their ticket with Trump in November.

So far, those conversations among vulnerable Democrats have been happening mostly behind the scenes, pointing to internal polling in their districts that showed a Sanders ticket hurting their own reelection chances.

“The conversations are all the same: ‘Oh s---,’” one Democratic lawmaker with a tough reelection battle said.

Most Senate Democrats are cautious to go after Sanders publicly, in part out of reluctance to criticize a colleague or repeat any animosity from 2016, when the Vermont independent ran against Hillary Clinton. They also acknowledge his ideas have influenced the party and see little upside in weighing in with the race seeming fluid.

“The conversations are all the same: ‘Oh s---." A Democratic lawmaker with a tough reelection battle

But some Senate Democrats have expressed concern about the effect Sanders could have on Democratic challengers in swing-state races. While Sen. Catherine Cortez Masto (D-Nev.), chairwoman of the Democratic Senatorial Campaign Committee, said Wednesday Democrats would coalesce around whoever the nominee is, others are not so sure.

“Sen. Sanders’ argument is that his candidacy will inspire and mobilize a whole new sector of our country that doesn’t typically vote,” added Sen. Chris Coons (D-Del.), a Biden backer.

But Coons argued that he has yet to see evidence of that based on voter turnout in Iowa, which was lower than expected. New Hampshire turnout, however, did set a new record on Tuesday.

“He may make it harder rather than easier for us to take back the Senate,” Coons said.

Coons, along with other Biden backers in the Senate, are standing by their candidate and downplaying the former vice president’s disappointing performances in Iowa and New Hampshire. They argue that the two states are not good barometers when it comes to appeal to voters of color and are showing no signs of wanting to ditch their candidate for someone like Bloomberg, Buttigieg or Klobuchar.

Sen. Bob Casey (D-Pa.) acknowledged Klobuchar had a “strong performance,” but he reiterated his support for Biden.

“They pointed out last night that 99 percent of African Americans and Latinos have not been heard from yet in the country,” he said. “ Let’s see what happens when you have a more diverse electorate.”

Nevada, which holds its caucus next week, has a large Latino population. South Carolina, where black voters make up a majority of the Democratic electorate, will hold its primary the next week.

“The media is trying to anoint a nominee at this point when it’s really still pretty early and there’s some really good candidates out there,” added Doug Jones of Alabama, the most vulnerable Democratic senator.

“Joe is resilient, he has had more bouncebacks in his life than most people could ever dream about… so I’m not too worried," Sen. Doug Jones said. | Scott Eisen/Getty Images

Jones, who is close to Biden, has conceded that a Sanders nomination would make his reelection tougher. “Joe is resilient, he has had more bounce backs in his life than most people could ever dream about … so I’m not too worried.”

Still, support for Biden had already been fraying at the edges even before Iowa, with some Democrats on Capitol Hill noting his poor performance at the polls as well as what they saw as declining energy on the campaign trail and on debate stages.

Biden still holds the most congressional endorsements among any candidate, though some Democrats suggest that support could erode if he underperforms again in the next two nominating contests.

“If Biden announced today that he was going to drop out, you’d have an avalanche of African Americans around the country going to Bloomberg,” said Rep. Emanuel Cleaver (D-Mo.), who endorsed Biden last September and plans to stick with him.

“It would be foolish for anyone to say what happened in Iowa and New Hampshire is not going to have an impact, it will,” Cleaver said of Biden’s performance in the past 10 days. “There’s no question Nevada is extremely important.”

Burgess Everett and Laura Barron-Lopez contributed to this report.

