As Senator Bernie Sanders and his supporters revelled in his victory in the New Hampshire primary on Tuesday, Jimmy Tawater’s mood was less celebratory.

“I love Bernie Sanders. Love Bernie, love his ideas. But he can’t win,” said Mr Tawater, 72, of Ringgold, Georgia.

Late on Tuesday, Lloyd Blankfein, the former Goldman Sachs chief executive, wrote on Twitter that the Vermont senator would “ruin our economy” if elected president.

And on Capitol Hill on Wednesday, representative Dean Phillips, a centrist Democrat from Minnesota who flipped a Republican House seat in 2018, said he was worried that Mr Sanders would doom his re-election campaign — and cost Democrats their House of Representatives majority.

“I’m the first Democrat to win in my district since 1958,” said Mr Phillips, who backs his home state senator, Amy Klobuchar. “I attracted a lot of independent and moderate Republican support, many of whom probably voted for a Democrat for the first time in a long time. And while I respect Bernie Sanders as a senator, as a candidate, his candidacy is very challenging for people who come from districts like mine.”

Democratic candidates compete on the campaign trail: In pictures Show all 18 1 /18 Democratic candidates compete on the campaign trail: In pictures Democratic candidates compete on the campaign trail: In pictures Jessica Canicosa, a precinct captain for Bernie Sanders, waits to greet caucus voters at Liberty High School in Henderson, Nevada REUTERS Democratic candidates compete on the campaign trail: In pictures Hotel workers at the Bellagio in Las Vegas get to grips with voting papers during the Nevada caucuses AFP via Getty Images Democratic candidates compete on the campaign trail: In pictures A caricature of Bernie Sanders is projected on to a tree during a rally in Las Vegas EPA Democratic candidates compete on the campaign trail: In pictures A woman waits to have a photo taken with Elizabeth Warren during a town hall meeting in Las Vegas REUTERS Democratic candidates compete on the campaign trail: In pictures The threat of coronavirus and other germ-borne illnesses was on some voters' minds at the Democratic caucuses in Henderson, Nevada Getty Images Democratic candidates compete on the campaign trail: In pictures Former vice-president Joe Biden takes a selfie with a voter in Las Vegas ahead of the Nevada caucuses REUTERS Democratic candidates compete on the campaign trail: In pictures Amy Klobuchar changes her shoes backstage after giving a speech in Exeter, New Hampshire AFP/Getty Democratic candidates compete on the campaign trail: In pictures A warmly-wrapped-up dog attends an Elizabeth Warren event at Amherst Elementary School in Nashua, New Hampshire AFP/Getty Democratic candidates compete on the campaign trail: In pictures Bernie Sanders, who romped to victory in New Hampshire against Hillary Clinton in 2016, talks to the media in Manchester Getty Democratic candidates compete on the campaign trail: In pictures Joe Biden was hoping to improve on his poor showing in Iowa in the New Hampshire primary Reuters Democratic candidates compete on the campaign trail: In pictures Elizabeth Warren, renowned for giving time to supporters for selfies, works the crowd at the University of New Hampshire in Durham Getty Democratic candidates compete on the campaign trail: In pictures Joe Biden takes a selfie with a supporter and his child outside a campaign event in Somersworth, New Hampshire on 5 February Reuters Democratic candidates compete on the campaign trail: In pictures Elizabeth Warren and Bernie Sanders quarrel after a confrontation in a TV debate in which Sanders claimed that Warren was not telling the truth about a conversation in which she claimed he had said a woman could not win the presidency on 14 January AP Democratic candidates compete on the campaign trail: In pictures Supporter Pat Provencher listens to Pete Buttigieg in Laconia, New Hampshire on 4 February Getty Democratic candidates compete on the campaign trail: In pictures Pete Buttigieg speaks at a campaign event in Concord, New Hampshire while awaiting the results of the Iowa caucus Reuters Democratic candidates compete on the campaign trail: In pictures Elizabeth Warren is presented with a balloon effigy of herself at a campaign event in Nashua, New Hampshire on 5 February Reuters Democratic candidates compete on the campaign trail: In pictures A Trump supporter rides past a rally for Amy Klobuchar in Des Moines, Iowa on 14 January AP Democratic candidates compete on the campaign trail: In pictures A man holds up a sign criticising billionaires in the presidential race in front of Michael Bloomberg in Compton, Califronia. The former New York mayor skipped the first caucus in Iowa and instead campaigned in California on 3 February Reuters

Forty-eight states have yet to render judgment on Mr Sanders and the other candidates seeking the Democratic nomination for president. But with Mr Sanders solidifying his standing at the top of the field, concerns about his electability and whether a possible Mr Sanders nomination might alienate some swing voters rippled through different corners of the country on Wednesday — from Wall Street to the halls of Congress to the Bessie Smith Cultural Centre in downtown Chattanooga, where more than 1,000 people turned out in the rain to hear Michael Bloomberg speak.

Jenny Gaines of Chattanooga couldn’t help doubt whether the Democratic Party was in a healthy place. “We’re very divided,” Ms Gaines, 58, said. “And let me say this: If we don’t come together, Trump is going to be back in office.”

Mr Sanders has now won the most votes in the first two nominating contests, energizing many liberal voters by championing “Medicare for All” and free public colleges and fighting against income inequality and climate change. He has also proposed sharp tax increases on the wealthiest Americans and on corporations to pay for much of his agenda, and he has been a sharp critic of Wall Street excesses.

Mr Sanders, in turn, unsettles many upper-income and moderate Democrats who worry about the political, economic and personal consequences if a self-described democratic socialist becomes president. Some Wall Streeters compared Mr Sanders to failed candidates like Jeremy Corbyn, the British Labour Party leader who was soundly defeated by prime minister Boris Johnson in a recent election.

Mike Novogratz, a Goldman Sachs alumnus who runs the merchant bank Galaxy Digital, said Mr Sanders’ oppositional nature had prompted “too many friends” to say they would vote against him in November. “And they hate Trump,” he said.

Sanders supporters react during a Primary Night event at the SNHU Field House in Manchester New Hampshire on 11 February 2020 (Timothy A Clary/AFP/Getty Images)

In Washington, the anxiety is particularly acute among a small but politically important group of freshman House Democrats who helped their party win control of the House in 2018 by flipping Republican seats in districts that President Donald Trump won in 2016. Now, they fear that having Mr Sanders at the top of the ticket could endanger them with the independent-minded voters who dislike Mr Trump but would probably not vote for a self-described democratic socialist.

But concern is also building among centrists in the Senate, where Democrats face an uphill battle in their quest to flip the four Republican seats they would need to regain the majority, and must defend moderates like senator Jeanne Shaheen of New Hampshire. Senator Shaheen, who has not endorsed any candidate, said she was not concerned by Mr Sanders but sounded frustrated on Wednesday by the suggestion that he had won big in her state.

“He did not win big!” she exclaimed. (Mr Sanders took about 26 per cent of the vote, just ahead of Pete Buttigieg, the former mayor of South Bend, Indiana.)

In the House, members of the group of about three dozen moderates — often called “front-liners” or “majority-makers”— have toiled to carve out political identities distinct from their party’s progressive base, and most are facing competitive re-election challenges from Republicans who bill them as radicals who have empowered a far-left agenda in Congress.

Eight of the front-line Democrats, including Representatives. Haley Stevens of Michigan, Max Rose of New York and Lucy McBath of Georgia, have endorsed Mr Bloomberg, the former New York City mayor. Others, including several military veterans — representatives Conor Lamb and Chrissy Houlahan of Pennsylvania, and Elaine Luria of Virginia — are coalescing around former vice-president Joe Biden.

Two former chairmen of the party’s House campaign arm — Steve Israel, who has endorsed Mr Biden, and Rahm Emanuel, who is not backing any candidate — said the lawmakers were right to be worried. Mr Emanuel, the former mayor of Chicago, led Democrats to retake the House in 2006 using a playbook he called “metropolitan majority” — a “centre-left” agenda aimed at uniting urban and suburban voters.

“Back in 2006, we created Red to Blue as a political entity,” Mr Emanuel said, referring to a program Democrats made to help candidates flip Republican seats. “We never established or created ‘blue to deep blue.’ That’s not how you create majorities.”

Mr Israel sees two reasons for concern: The race for president will be won or lost in seven swing states and about 20 to 30 swing counties. And the “down-ballot effect” — the tendency for the candidate at the top of the ticket to dominate voters’ assessments of other candidates of his or her party — is very strong in a presidential race.

“Donald Trump will paint every Democrat — whether they’re running for US Senate or county sheriff — as a socialist, as a ‘Bernie Sanders socialist,’ ” he said, “and that’s a tough deal in a lot of these districts.”

Anxiety in the Democratic Party is exactly the sentiment that Mr Bloomberg hopes will propel his unorthodox presidential bid. He is the only candidate who is skipping the four states that vote first in the nominating process — Iowa, New Hampshire, Nevada and South Carolina. Instead, he has been campaigning and spending heavily on advertising in states like Tennessee that vote in the 3 March Super Tuesday contests.

And while the candidates trying to appeal to the country’s political middle — Joe Biden, Amy Klobuchar and Pete Buttigieg — jockey for advantage in the early states, Michael Bloomberg is betting that enough voters will come to see him as the consensus alternative to Sanders.

“I’m a believer that if we’re going to unite this country, we should unite the whole country,” Mr Bloomberg said on Wednesday. “So I’ve been going to small states as well as big states, states that are on Super Tuesday and states that don’t vote for a long time.”

Over the next several weeks, Mr Bloomberg plans to campaign heavily, starting on Wednesday in Tennessee before going to North Carolina and Texas on Thursday, then Virginia on Saturday. All four states vote on Super Tuesday.

Speaking to reporters in Chattanooga, Mr Bloomberg said he saw nothing productive about joining in the criticisms of Mr Sanders. And in a speech to prospective voters, he made an appeal for unity. “The stakes couldn’t be higher,” he told the crowd, only 500 members of which made it into the main room to hear him speak while 500 more waited in an overflow room or stood outside in the rain. “The way to defeat Trump is by appealing to the broadest possible coalition — Americans of all backgrounds and parties — to stand shoulder to shoulder.”​