Sen. Bernard Sanders’ surprisingly strong candidacy for president has laid bare a sharp division within the Democratic coalition, pitting its activist base against the moderate-minded establishment.

It’s a split Republicans — especially the ones focused on winning down-ballot races this fall — are now racing to exploit.

The GOP is betting that the ideological fight at the top of the Democratic ticket will filter down the ballot, exposing incumbents and establishment-favored candidates to thorny questions about their support — or lack thereof — of the self-described socialist and his polarizing agenda. The idea: Either candidates disavow support for the Vermont senator and alienate supposed progressive allies, or they embrace Sanders and suffer the consequences in November when Republicans tie them to politically problematic issues such as single-payer health care. In effect, it mirrors the approach Democrats have taken in recent presidential elections, when they have successfully tied Republican candidates to the sometimes damaging positions of their party’s standard-bearer.

The strategy has special resonance now, after Sanders’s unexpectedly strong second-place showing in the Iowa caucuses. And for a party whose candidates have been relentlessly pressed for months about Donald Trump, there’s a palpable sense of relief and delight in giving Democrats a presidential headache of their own — one they hope lasts beyond even Sanders’s White House bid.

“Socialism is a pretty hard sell to Americans who go to work and collect a paycheck,” said Josh Holmes, a Republican strategist and Senate Majority Leader Mitch McConnell’s former chief of staff. “Regardless of whether Sanders is the nominee or not, Democrats are going to be ‘feeling the Bern’ in an entirely different way when they try to explain this to voters next fall.”

Democrats say they aren’t worried, arguing Sanders — still a heavy underdog to win the Democratic presidential nomination — is hardly the bogeyman that Trump is. But Republicans say there is ample evidence the conversation about Sanders and his agenda already has bubbled up into Democratic primaries.

In Pennsylvania, for instance, a debate last month among the three candidates seeking the Democratic nomination — former Rep. Joe Sestak, Braddock Mayor John Fetterman and onetime gubernatorial candidate Katie McGinty — veered into a topic that’s become closely associated with Sanders’s campaign: single-payer health care. The senator from Vermont has made overhauling the nation’s health care system central to his campaign despite criticism from even some Democrats, including Hillary Clinton, that the plan is unfeasible and politically damaging in the general election. McGinty and Fetterman praised the concept of a single-payer system, though both said they wanted to preserve the existing system.

And in Wisconsin, the presumed Democratic nominee for Senate, former Sen. Russ Feingold, has faced a flurry of questions recently about his former Senate colleague. At a January forum hosted by Marquette University Law School, Feingold — who has not endorsed for president — praised Sanders profusely.

“He’s an honorable person,” Feingold said. “He’s a committed progressive. I agree with him on many issues.

“In fact, Bernie and I were holding out for an even stronger bill on the Affordable Care Act. We wanted a single-payer,” he added, before catching himself. “We wanted an option, an option to opt in, a public option.”

Asked whether the former senator supports a single-payer approach, Feingold spokesman Michael Tyler said “there can be an honest debate about how to achieve” universal coverage. But the spokesman hastened to add that if Feingold were to win back his Senate seat, he does not plan to introduce single-payer legislation or push for its adoption.

“Right now, Russ is focused on increasing access to health care through the framework of the ACA,” Tyler said.

Linking Democratic candidates to both Sanders personally and his agenda — in particular his health care overhaul — is part of the GOP’s formula. And it mirrors the plan of attack used by Democrats during Trump’s rise to the top of the polls. For months, Democratic operatives have pushed Republican candidates whether they plan to support the New York billionaire should he become the party’s presidential nominee. And every time he has said something controversial — such as his proposal to ban Muslim immigration to the United States — incumbents such as Sens. Pat Toomey of Pennsylvania and Rob Portman of Ohio were asked if they agreed.

Democrats, for their part, are dismissive of the new strategy, believing that Sanders hasn’t left as large an impression on the public as Trump or even Ted Cruz – and was much less likely to eventually win the nomination than either.

Even if voters are paying close attention to the lawmaker from Vermont, they argue the conversation he’s sparking is categorically different than the one Trump has started. Getting a question about single-payer, for instance, starts a conversation about improving access to health care — topics Democratic operatives say they are happy to discuss.

“The Democratic nominees for president and our Senate candidates around the country are leading an important conversation about issues like college affordability, the wage gap and overall economic security for middle-class families,” said Sadie Weiner, spokeswoman for the Democratic Senate Campaign Committee. “But Republican Senators and Senate candidates are being forced to answer for their toxic Presidential frontrunners, who have alienated moderate and swing voters by describing Mexican immigrants as criminals and rapists and calling to ban all Muslims from entering the country. There’s no comparison.”

The best test case for the strategy might come in Wisconsin. Feingold — who before losing re-election in 2010 was considered one of the party’s strongest voices in favor of the muscular brand of liberalism championed by Sanders — is a favorite target of Republicans because of his close ties to Sanders. An organization staffed by Feingold loyalists has backed Sanders before: In January 2015, before the Vermont Democrat started running for president, the group donated $1,000 to his campaign. The group, Progressives United, listed Sanders alongside Massachusetts Sen. Elizabeth Warren as one of its “champions” on its website.

Any Sanders-related damage done to Feingold would come in the general election — he is running uncontested in the primary. But Senate Democrats have a handful of potentially competitive primaries this year, including in Pennsylvania, Florida, and — to a lesser extent — Ohio and Illinois. Sanders’s popularity could present problems to the candidates running in those states, forcing some of them to choose between alienating his supporters in a primary and more moderate voters in a general election.

Republicans advise that in many of these cases, the questions about Sanders will happen naturally between sparring campaigns and an inquisitive media. In fact, according to some of the party’s strategists, staying hands-off might be a better approach.

“I don’t think you do anything very blatant yet,” said one senior Republican strategist, who asked for anonymity to speak candidly about party strategy. “It’s more powerful if Democrats are fighting each other. So do it more behind the scenes, at least for now.”

Contact Roarty at AlexRoarty@cqrollcall.com and follow him on Twitter at @Alex_Roarty.

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