Moderate Democrats who were alarmed by the prospect of self-described democratic socialist Bernie Sanders winning the nomination returned to the Capitol Wednesday with a newfound spring in their step, celebrating Joe Biden's come-from-behind victories on Super Tuesday

The mood among Democrats from swing districts and red states wavered between relief, surprise and giddiness after Biden won 10 out of the 14 states and put the brakes on Sanders' march to the Democratic nomination. Democrats in down-ballot races used words like "cloud nine," "euphoria" and "unprecedented" to describe Biden's stunning turnaround.

“I think a lot of people are relieved that we have a candidate and it’s somebody who has now demonstrated that he can unify disparate elements of the Democratic Party and attract disaffected Republicans," said Rep. Tom Malinowski, D-N.J., a swing district Democrat who endorsed Biden.

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Another moderate Democrat who had been sounding the alarm that a Sanders' nomination could cost Democrats the House was joyful Wednesday.

"We got a little bounce in our step," said the Democrat from a swing district, who asked for anonymity to speak freely. "We went in last night thinking that it's going to be a tough night, and we came out on cloud nine.”

Rep. Donna Shalala, a freshman rep who flipped Florida’s 27th district from red to blue in 2018, said Biden’s comeback was “pretty spectacular.” She was convinced Sanders couldn't be the nominee because of his embrace of socialism and his kind words for Fidel Castro's dictatorship.

“I kept I keep saying to my friends, Bernie is not going to be our candidate. My district is so anti-Bernie because of his position on Cuba and Venezuela, Nicaragua, and everything else,” Shalala said.

SUPER TUESDAY RESULTS

"We weren't quite freaking out but we were concerned,” Shalala said of swing-district Democrats. “He was not popular in our districts. In my district in South Florida, he was very unpopular. My district is 70 percent Hispanic. Most people came from one of those countries that he likes."

Several Democrats described the last few days as a roller coaster ride. On Wednesday, they were in happy disbelief that Sanders' momentum to the nomination had been thwarted.

Rep. Emanuel Cleaver, D-Mo., said many House Democrats Wednesday have feelings of “elation [and] euphoria. I think people actually are more fired up today than they were maybe since Obama won South Carolina," said Cleaver, who credited Rep. Jim Clyburn's pivotal endorsement of Biden before the South Carolina primary for changing the tide.

"I think people are just elated," Cleaver added. "That will help ignite turnout. Every time you win, it creates the possibility of another win. And there is nothing more powerful in football and in politics than momentum.”

Biden lost Iowa, New Hampshire and Nevada and his campaign was on the brink of collapse until his firewall held in South Carolina. He trounced Sanders Saturday in South Carolina, 48 to 20 percent, with the strong support of African-American voters.

Then Pete Buttigieg and Amy Klobuchar dropped out and threw their support behind Biden, who picked up a string of other endorsements over the weekend. Heading into Super Tuesday, more moderate and establishment Democrats began to unite around Biden as their candidate -- sending a powerful message to voters on the fence that "this is our guy."

Sanders' supporters Wednesday found some bright spots -- namely winning the big delegate prize of California and building up support among Latino voters.

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But some faulted the so-called Democratic establishment for speaking out against Sanders in scary terms and "fear-mongering."

“I do think that the fear of a [continued] Donald Trump presidency was weighing heavy on everybody,” Rep. Pramila Jayapal, D-Wash., said. "There was a lot of -- I would call it -- fear-mongering from some people who have power and platform to say Bernie Sanders will ... somehow destroy our country or destroy our House majority. I think people for real reasons had to make a decision and they took that into account and they voted.”

Jayapal, a Sanders backer, faulted unnamed party leaders for scaring off voters and warned it could actually backfire on Democrats. "I also think it just shows a lack of leadership and, honestly, a lack of imagination to use those kinds of tactics."

President Trump, skilled at riling up dissension, has taken to calling the Democrats' efforts to stop Sanders a "coup."

While Sanders' allies won't go that far, they acknowledge people in power are working against the Vermont senator.

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Asked if the Super Tuesday result was a rebuke of Sanders and socialism, Rep. Rashida Tlaib, D-Mich., said “I don’t think it has anything to do with 'isms. I actually think it has a lot to do with people that make decisions that already have power."

Tlaib, a Sanders backer, said "I wouldn’t call it a coup ... but it makes me want to work harder.”

The next big test will be on Tuesday when Michigan, Idaho, Mississippi, North Dakota, Missouri and Washington state hold elections.