The rise of socialist Bernie Sanders is frustrating Never Trump Republicans who are hoping the Democratic Party nominates a consensus, center-left presidential candidate they are comfortable supporting in November. If Sanders is the Democratic nominee, many will sit out the election and be deprived of the opportunity of voting against President Trump, they said.

Sanders is surging days before the Iowa caucuses and a couple of weeks before the New Hampshire primary, leaving Republican operatives avowedly opposed to Trump worried and perplexed. Most are convinced swing voters in key battlegrounds would reject Sanders, paving the way for Trump’s reelection. They are also convinced the Vermont senator, 78, is simply too liberal to earn their vote. With a Sanders nomination, Never Trump Republicans are unsure of what comes next.

“I don’t know where the anti-Trump movement goes from there,” said Jennifer Horn, a Never Trump Republican and former New Hampshire GOP chairwoman who is affiliated with the Lincoln Project, a group of anti-Trump Republicans who have pressured GOP senators to support impeachment.

“It’s a really tough question,” added political strategist Sarah Longwell, a Never Trump Republican at the center of an unsuccessful effort to recruit a formidable candidate to challenge the president in the 2020 GOP primary.

Anti-Trump Republicans are holding out hope for 77-year-old Joe Biden.

The former vice president is a Democrat they can embrace, they said: liberal, but not too far left, and moderate in tone. Biden consistently polls well against Trump and leads the Democratic field nationally. He now trails a climbing Sanders in the Feb. 3 Iowa caucuses and the Feb. 11 New Hampshire primary, but he leads in the other critical early states and is better positioned to win the party’s crown than other contenders they could stomach, such as Pete Buttigieg, Sen. Amy Klobuchar of Minnesota, and Mike Bloomberg.

If Biden wins the nomination, many Never Trump Republicans are prepared to work on his behalf to attract disaffected voters on the Right just like them, but Never Trump Republicans have limits. Philosophically conservative and not wanting to be perceived as otherwise, they view Sanders’s self-professed "democratic socialism" as equally problematic and might skip 2020 altogether if he leads the Democratic ticket.

“It’s asking a lot from people on the center-right or in the old Reagan wing of GOP to go full Sanders in November,” said Jerry Taylor, who runs the Niskanen Center, a Washington think tank that has become a hub for the Never Trump community. Taylor does plan to support Sanders in the general election if the senator wins the Democratic nod but described himself, and others like him, as the exception to the rule.

“I would not feel particularly happy about it, but I would swallow hard and pull the lever,” Taylor said.

Should Sanders emerge, Never Trump Republicans say they and independent conservatives itching to oust Trump in the fall are likely to sit on their hands or vote for a hopeless third-party candidate in protest.

That is what Longwell concluded after two years and several focus groups with persuadable voters in the Rust Belt as part of her extensive research into the best strategy for holding Trump to a single term.

Longwell conceded Sanders would juice the liberal base, but she said his plans for expansive government and European-style foreign policy would scare away the voters he needs in the Midwest to produce an Electoral College majority. This includes the soft Republicans, suburban swing voters, and college-educated women who often voted GOP in the past but supported mainstream Democrats in droves in the midterm elections.

“Bernie Sanders will get beaten by Donald Trump,” Longwell said. “He’s a nonstarter for swing voters.”