Democratic presidential candidate and former Vice President Joe Biden speaks at a campaign event Wednesday in Somersworth, N.H. Elise Amendola/Associated Press

SOMERSWORTH, N.H. — Facing questions about his campaign’s viability, Joe Biden escalated his criticism of his top Democratic rivals on Wednesday, suggesting both Bernie Sanders and Pete Buttigieg were risky choices for a party desperate for a return to the White House.

Biden conceded that he was disappointed by his sagging performance in the leadoff Iowa caucuses, calling it a “gut punch” for his campaign. As he turned his attention to New Hampshire, he sought to reenergize his campaign by drawing sharper contrasts with those who led in Iowa, including casting Sanders – a self-described democratic socialist – as a drag on others in the party.

“If Sen. Sanders is the nominee for the party, every Democrat in America up and down the ballot, in blue states, red states, purple states and easy districts and competitive ones, every Democrat will have to carry the label Sen. Sanders has chose for himself,” Biden said.

Biden was equally blunt about his assessment of Buttigieg, saying he didn’t think the Democrats’ standard-bearer against President Trump should be someone who hasn’t been elected to a higher office than mayor of South Bend, Indiana, a city of about 100,000.

“It’s a risk, to be just straight up with you,” he said.

The tough talk comes as Biden’s third presidential bid enters a critical stretch. He needs to bounce back from what partial results suggest could be a fourth place finish in Monday’s Iowa caucuses. Biden trailed Buttigieg and Sanders, according to partial returns. He was also trailing Sen Elizabeth Warren of Massachusetts.

That leaves some establishment Democrats, including some Biden supporters, questioning his contention that he’ll reclaim clear front-runner status in the race once the primary fight moves beyond overwhelmingly white Iowa and New Hampshire to more racially diverse electorates.

“If he came in fourth, yeah, that could hurt,” said Bill Freeman, a Biden donor from Nashville, Tennessee, who added that he hadn’t even considered such a possibility heading into Monday’s caucuses. “That’s a bad night, no matter how you spin it.”

Most precarious for Biden: Some of the would-be donors he could win over with a strong showing are giving new looks to Michael Bloomberg, the former New York City mayor whose entire strategy of sitting out the four early nominating states is pegged to the possibility that Biden falters. Bloomberg, one of the world’s wealthiest men with a net worth approaching $60 billion, isn’t asking for money. He’s simply looking for support that could cut off financial lifelines to Biden, whose campaign reported just $9 million cash on hand to start the year.

That’s patronage Biden needs to remain competitive with Buttigieg, as well as Warren and Sanders, who have raised massive sums from small-dollar online contributors who have been far less generous to Biden.

Alex Sink, a Democratic donor who hosted Hillary Clinton in the 2016 race, said many donors are holding back, waiting to see how Biden does. They are also keeping an open mind about Bloomberg, whose campaign asked Sink last week to attend an event in Tampa.

“I was anxious to do it because, like so many others, I’m curious and interested and worried about who our candidate will be and how we are going to beat Trump,” she said. “Most of my friends don’t know yet who they are voting for.”

In New Hampshire on Tuesday, Biden insisted he had a “good night” in Iowa. But he was more frank Wednesday during the event in Somersworth.

“I am not going to sugarcoat it, we took a gut punch in Iowa,” Biden said. “But look, this isn’t the first time in my life I’ve been knocked down.”

Biden aides have said for months that he didn’t have to win in Iowa or on Feb. 11 in New Hampshire because he was better positioned in Nevada’s Feb. 22 caucuses, South Carolina’s Feb. 29 primary and a slate of March 3 primaries, when more than a third of Democrats’ national delegates are at stake.

That never meant, however, that Biden could sustain a bad showing in Iowa and New Hampshire. The approach was also an expensive one, requiring deep campaign reserves to finance advertising and staffing in Nevada, South Carolina and delegate-rich states like California and Texas.

Biden has a campaign footprint across the March primary map, with paid staff or volunteer offices in 13 states. But his cash flow raises questions about how much he can bolster his existing operation. His uneasy financial situation is underscored by an affiliated super PAC that spent more on Iowa ads than the campaign itself, but still has struggled to raise money and has little left over after Iowa.

“Will he have as much money as Bernie Sanders? Probably no. But it doesn’t matter – all you need is enough gas to finish the race,” said John Morgan, a Florida plaintiffs attorney and one of Biden’s top fundraisers.

Freeman and Morgan agreed that Biden needs to finish in the top three in New Hampshire and ideally as the top moderate. That reflects what had been the quiet hope of Biden’s team heading into Monday’s Iowa caucuses. They didn’t necessarily expect to win outright. But they hoped that they could emerge from Iowa as the clear alternative to Sanders, a democratic socialist and leader of the left’s progressive base.

An effectively two-person race between Sanders and the former vice president, Biden confidants believed, would open the financial spigot, firm up his advantages among nonwhite voters and win over skeptical white moderates now aligned with Buttigieg or Sen. Amy Klobuchar.

“That’s my conversation with people: If Bernie Sanders is the nominee, would you vote for him?” Morgan said. “If not, then back Joe.”

Biden took the same approach Tuesday on the campaign trail, hammering Sanders as directly as he has in weeks. “It’s time to get real about health care,” he said as he compared his proposal to expand existing insurance markets with a “public option” with Sanders’ “Medicare for All” idea. Sanders has been pushing single-payer insurance for “30 years now,” Biden said, and ”hasn’t moved it an inch.”

The problem, Freeman said, is that a lackluster start in Iowa makes the Biden-Sanders juxtaposition a much harder sell. “I don’t think any of those conversations are happening today” with potential new donors, he said.