This article originally appeared on VICE US.

House Democrats are panicking that a Bernie Sanders nomination could hand President Trump unified control of Washington next year.

Democrats took the House in the 2018 midterms by sweeping through suburban districts, buoyed by a huge swing their way from college-educated white women and upscale, fiscally moderate voters appalled by Trump. Those voters don’t like the Vermont senator and self-described democratic socialist nearly as much as they like most of the rest of the Democratic field. And it’s the Democrats in those districts who are freaking out right now that Sanders has emerged as the clear front-runner to be their party’s presidential nominee, based on his strong showing in the early primary states and expectations heading into Saturday’s South Carolina primary and Super Tuesday next week.

“Sanders as the Democratic nominee would create a problem for a lot of the moderate districts,” said Rep. Stephanie Murphy (D-Fla.), who flipped a historically Republican seat in suburban Orlando in 2016. “Upscale, college-educated districts do not support socialism."

Murphy, the co-chair of the moderate Blue Dog Democrats, initially backed Beto O’Rourke and now supports former New York City Mayor Mike Bloomberg. She’s worried that if Sanders is the nominee, it could crush her party’s hard-won majority. Democrats have an 18-seat majority in the House right now, including 30 seats that Trump won in 2016. Many of those seats are held by freshmen — the vast majority of the 41 seats Democrats flipped in the midterms were in suburban territory where voters tend to be wealthier and more educated than the country as a whole.

It’s telling that none of the 42 members in the seats that House Democrats have on their “Frontline” program for vulnerable incumbents have endorsed Sanders. Former Vice President Joe Biden has nine backing him, and Bloomberg has seven. Billionaire businessman Tom Steyer is the only other Democrat who made the stage at Tuesday night’s debate in South Carolina who doesn’t have any endorsements from this group.

"Reverse coattail effect"

Former Rep. Steve Israel (D-N.Y.), who ran House Democrats’ campaign efforts in 2010 and 2012, said he was hearing fears from his former colleagues that Sanders would “wipe them out” and give the Republicans unified control of Washington once again.

“There will be a reverse coattail effect if Bernie Sanders is the head of the ticket,” he said. “Democrats in the 30 Trump districts and 41 districts that flipped in the midterms have a much more severe challenge than they would otherwise.”

Anti-Sanders panic from moderates has flared up hard this week. After his dominant showing in Nevada’s caucuses last weekend cemented his front-runner status, Sanders drew sharp rebukes for a pair of comments from a number of Democrats whose wins helped hand their party the House last election.

The Vermont senator’s most controversial comment was highlighting Fidel Castro’s literacy program in Cuba as he defended his past positive comments about Cuba’s brutal regime during a Sunday 60 Minutes interview. He doubled down on those remarks in Tuesday’s debate.

Freshman Rep. Debbie Murcarsel-Powell (D-Fla.), who represents a Cuban-heavy Miami-area district and hasn’t endorsed a candidate, tweeted that she found Sanders’ statement on Cuba “absolutely unacceptable.” She was joined by Rep. Donna Shalala (D-Fla.), a freshman from a neighboring district, who tweeted a GIF a cat saying “c’mon bro,” while asking Sanders to “speak to some of my constituents before he decides to sing the praises of a murderous tyrant like Fidel Castro.”

Sanders also drew heat for saying he wouldn’t attend the annual conference of the American Israel Public Affairs Committee (AIPAC), a right-leaning pro-Israel lobbying group, because it provides a platform for "leaders who express bigotry and oppose basic Palestinian rights.”

Rep. Josh Gottheimer (D-N.J.), who supports Bloomberg, tweeted that Sanders “owes an immediate apology for his appalling comments.”

Clear breaks

Other freshmen from districts Trump won have already sought clear breaks with Sanders: Rep. Anthony Brindisi (D-N.Y.) said he wouldn’t back Sanders if he’s the nominee, and Rep. Joe Cunningham (D-S.C.) declared that “South Carolinians don’t want socialism” and attacked “Bernie’s proposals to raise taxes on almost everyone.”

Public polls don’t support moderates’ panic about how Sanders would fare nationally — at least not yet. As Sanders pointed out during Tuesday night’s debate, he’s beating Trump in most head-to-head polls. But Sanders is just starting to get a taste of the type of vetting reserved for presidential front-runners. And he’s got some major problems with the type of voters who powered Democrats’ 2018 blue wave.

A recent Washington Post-ABC News poll found Sanders with a six-point national lead over Trump among registered voters, similar to the leads held by Bloomberg and Biden and larger than the ones held by Buttigieg, Klobuchar, and Warren.

But Sanders leads Trump by just two points with college-educated white women in that poll. Every other Democrat besides Elizabeth Warren has a double-digit edge over Trump among that group. White women with a college degree backed Democrats by a 20-point margin in 2018, according to exit polls.

Sanders also ties Trump among voters from households making over $100,000, while Bloomberg, Buttigieg and Biden all hold leads of three to four points among that group.

Even Democrats who think Sanders can win the presidency say he’s got a lot of work to do with these groups to make sure Democrats don’t lose the House.

“He'll need to make sure he's doing more to reach out in particular to those women, suburban women that were really the benchmark of us taking over the House in 2018,” Guy Cecil, the head of the Democratic super PAC Priorities USA, told reporters Tuesday morning during a presentation of new polling that found a tossup race between Trump and Democrats.

Bernie's suburban problems

Republicans, meanwhile, are suddenly feeling giddy. Their candidates have been outraised by Democrats by wide margins and Trump’s suburban standing is still terrible, so GOP operatives have had little hope they could flip the House back next year. But Sanders’ own suburban problems could change that.

“Bernie as the nominee immediately puts a long line of suburban districts online for Republicans,” said Calvin Moore, a spokesman for the Congressional Leadership Fund, House Republicans’ main super PAC. “No matter what message those suburban voters were looking to send in 2018, they certainly are not looking for the type of wholesale, upending of their lives that socialism would bring.”

Sanders’ Democratic opponents have been increasingly harping on Sanders’ down-ticket danger. Biden, Buttigieg and Bloomberg all brought up the risk that Sanders could not only reelect Trump but give him unfettered control of Washington during Tuesday night’s debate.

On Tuesday, Bloomberg’s campaign released polling of the 42 front-line districts that showed Sanders trailed Trump by a point in the heading into 2020. Sanders’ numbers were underwater in the poll, with 38% holding a favorable of him to 53% holding an unfavorable, while Trump’s were only 47%-49%. After poll respondents were read a negative message about Sanders’ socialism, the verbal equivalent of an attack ad, he fell behind Trump by six points.

Partisan polls should always be taken with a grain of salt and one-sided message testing like Bloomberg’s — hitting Sanders without hitting Trump. But as Sanders’ Democratic critics point out, he’s just starting to face the type of serious vetting and attacks he’ll see in a general election against Trump.

“Of course his numbers go down with negative messaging — but no one’s hit him yet,” said Rep. Scott Peters (D-Calif.), another Democrat from an upscale suburban district who backs Bloomberg. “This is a great representation for why Trump is licking his chops. Once they get him in there, relatively unscathed from Democrats, they’re going to beat the stuffing out of him.”