Bernie Sanders’ win in New Hampshire should delight progressives, but it will not be without consequences. His victory has put a target on his back, supporters fear, with well-funded centrist Democrats and allied organizations sharpening their knives as they attempt to scupper his newly won frontrunner status.

Candidates including Joe Biden, Pete Buttigieg and Amy Klobuchar have repeatedly warned that Sanders would lose to Trump – despite evidence suggesting otherwise – but each has broadened their attacks in the past days to suggest that nominating Sanders would also spell disaster for House and Senate Democrats.

In the coming week, meanwhile, a Democratic Super Pac that spent $700,000 running anti-Sanders ads in Iowa is set to repeat the effort in Nevada, which votes on 22 February.

“You’re going to absolutely see significant money behind centrists, moderates, whatever, to defeat Sanders,” said Democratic strategist Andrew Feldman.

“Bernie is absolutely going to see intensified scrutiny. He was never in this position of the frontrunner in the 2016 race, and you’re going to see things from a long career come out that people are gonna go after.”

The Democratic Majority for Israel Pac ran an anti-Sanders campaign in Iowa, the week before the state’s caucus, highlighting the Vermont senator’s supposed unelectability against Trump, despite polls showing Sanders leading the president nationally. A Quinnipiac study released on 10 February showed Sanders eight points ahead of Trump – the biggest margin of any candidate other than the billionaire media mogul Mike Bloomberg.

Alongside the argument that Sanders would lose to Trump, what is becoming a more prevalent line of attack is the supposed impact a Sanders nomination would wreak on down-ballot Democrats.

Moderate members of Congress, who support Sanders’ rivals, have lined up this week to paint a dystopian vision of a Sanders nomination.

“Elected officials across the country understand there will be down-ballot carnage to the Democratic party if we elect the wrong person,” Congressman Cedric Richmond, a co-chair of Biden’s campaign, told the New York Times.

Dina Titus, congresswoman from Nevada and another Biden backer, suggested that with Sanders as the nominee “you’re not going to take back the Senate”.

“There’s not any way, because everybody’s going to be tarred with the same brush. We will probably lose seats in the House,” Titus said.

The claims have been echoed by Unite the Country, a Biden-supporting Super Pac. On Tuesday it sent a fundraising memo to donors, warning: “The legacy of the Sanders campaign (such as the Squad [a term given to four female progressive members of Congress, including Alexandria Ocasio-Cortez]) will ravage any chance Center-Left Democrats have of maintaining hard won victories in states from Pennsylvania to California.”

Many fear, however, that the main beneficiary of the brewing Democratic party civil war would probably be Donald Trump.

“The party and centrists and different factions within it have to be very careful about the way they go after Sanders, because it plays right into Trump’s hands if we look completely in disarray,” Feldman, the founder of Feldman Strategies, said.

“Comments about how people don’t like Bernie are not beneficial to our ultimate goal of beating Donald Trump.”

The claims that the leftwing Sanders would spell disaster for other Democrats are also tempered by the likelihood that Trump and his allies will portray whoever wins the nomination as an out-of-control socialist.

Trump has already characterized the Democratic party as a whole as the “Do Nothing, Radical Left Dems!”, whether referring to the House of Representatives, the Senate, Sanders or otherwise. It seems unlikely he will change his rhetoric even if the nominee is clearly not a member of the left.

Centrist Democrats also run the risk of alienating Sanders supporters ahead of November. Sanders has proved himself to be the only Democratic candidate capable of inspiring the same energy among his supporters as Trump, and the party risks alienating his swath of enthusiastic supporters across the country through further attacks.

“They’re here,” read the subject line of an email Sanders sent to supporters on Thursday. The message pointed to the planned Democratic Majority for Israel ad campaign in Nevada, but also to VoteVets, a Buttigieg-supporting Pac which is planning its own spend in the state.

“We’re not just competing with other candidates … we are competing with Super Pacs and billionaires too,” the Sanders email said.

“We’ve got the momentum. The political establishment and billionaire class know it. If our movement stands together, there is nothing we cannot accomplish.”

In campaign speeches, Sanders tells his supporters they must unite behind whoever is the Democratic nominee, but if Sanders supporters have spent months watching their candidate lambasted by the Democratic establishment, there should be concern about their reaction if Sanders misses out.

“I’m concerned that the more we alienate them the harder it’s going to be to unify for the general, and the reality is that we need everyone’s supporters here,” Feldman said.