House Speaker Nancy Pelosi has carefully managed every aspect of building and maintaining her Democratic majority — from leading fundraising efforts to crafting a policy agenda to making the reluctant decision to pursue the impeachment of President Trump.

But as many Democrats fear an existential threat to their control of the House in presidential candidate Bernie Sanders, Pelosi (D-Calif.) is suddenly finding herself in the unusual role of bystander as her party’s voters choose a nominee.

While a cadre of lawmakers and strategists are sounding alarms about the risks the senator from Vermont and democratic socialist would pose to down-ballot candidates, Pelosi is moving carefully publicly and privately to avoid even the perception that she is putting her thumb on the presidential scales.

“I think whoever our nominee is, we will enthusiastically embrace, and we will win the White House, the Senate and the House of Representatives,” she told reporters Wednesday morning as she entered a closed-door caucus meeting.

Inside the room, according to notes taken by a person present for her remarks who spoke on the condition of anonymity to describe the private meeting, Pelosi did not mention Sanders or any other candidate by name. Instead, she sounded a call for party unity amid the presidential rancor.

“I would hope that everyone would say, no matter who the nominee is for president, we wholeheartedly embrace that person,” she said, mentioning the stakes in state and local races ahead of the coming post-census redistricting cycle. “We led the way in 2018. We will lead it now, and, again, until everybody else has their houses in order. But we cannot show any division. This has to be about unity, unity, unity.”

Among her caucus, the prospect of a Sanders nomination is politically frightening — including to some of Pelosi’s closest House allies.

“I think that we’re all at risk with Bernie,” said freshman Rep. Donna Shalala (D-Fla.), who warned that Sanders’s comments praising some aspects of the communist regimes in Cuba and other Latin American countries would put electoral votes and House seats in Florida, a key swing state, at risk.

House Majority Whip James E. Clyburn (D-S.C.) became the highest-ranking congressional Democrat to tender a presidential endorsement Wednesday when he backed former vice president Joe Biden days ahead of the primary in Clyburn’s home state. He later told reporters at the Capitol that the endorsement was inspired partly out of down-ballot concern.

Asked whether a Sanders nomination could cost Democrats the House majority, Clyburn said, “I don’t know if he would or not — that’s not a chance I want to take.”

But according to interviews with a half-dozen members and aides allied with Pelosi and familiar with her thinking, past and present, it would be a mistake to expect Pelosi to follow Clyburn’s lead and insert herself into the presidential race.

Such a move, they said, would not only go against her practice, dating back more than 16 years, of not endorsing in the presidential primary, but it would also undermine her leadership of a diverse caucus in which opinions range from fervent support for Sanders to strong backing for Biden and other more centrist candidates — not to mention a donor base that runs the same gamut.

“She’s not going to get involved,” said Rep. C.A. Dutch Ruppersberger (D-Md.). “You’ve got to reach the needs, if you’re the leader, of all the different people, and give them their forum. So you have to let the process work its way out.”

Another Democrat who has talked with Pelosi and spoke on the condition of anonymity to frankly describe private conversations said she has been more concerned about the tenor of the recent debates — which have featured nasty attacks among the candidates — than Sanders’s potential impact down ballot.

Rep. Pramila Jayapal (D-Wash.), one of Sanders’s most prominent congressional supporters, said leaders have to be mindful of the next internal election when they take sides in a contest as divisive as the pending presidential race — and she praised Pelosi for maintaining her neutrality.

“I think that weighing in would not be appropriate for the speaker,” Jayapal said. “I think she plays a very important role in staying neutral and calming everybody down, to remember that our ultimate responsibility is to the voters.”

But the pressure on Pelosi to get involved only stands to grow in the coming weeks and months. The concern was aired on the presidential debate stage Tuesday night in South Carolina, where candidate Pete Buttigieg warned in stark terms that a Sanders nomination would put the House at risk.

The former South Bend, Ind., mayor said a Sanders nomination would mean “four more years of Donald Trump, Kevin McCarthy as Speaker of the House, and the inability to get the Senate into Democratic hands. The time has come for us to stop acting like the presidency is the only office that matters.”

As it happens: McCarthy (R-Calif.), the House minority leader, signaled Wednesday the GOP would move immediately to tie congressional Democrats to Sanders by forcing a vote this week on a resolution condemning Sanders’s comments praising some aspects of Cuban dictator Fidel Castro’s regime: “Do they stand with Bernie, or do they stand for freedom?” he said to reporters.

Should Sanders continue his march to the nomination, vulnerable Democrats will be forced on a near daily basis to reconcile their own views with those of Sanders, who, among other positions, supports a single-payer health care system, free public college for all, legalization of marijuana use and the sweeping economic and environmental reorientation known as the Green New Deal.

“Those are the problems they’re facing — how do they run while opposing the person at the top of the ticket?” said Jonathan Kott, a former senior aide to Sen. Joe Manchin III (D-W.Va.) and the executive director of the Big Tent Project, a nonprofit group that is running ads attacking Sanders. “It’s the signature issues of his platform. This is not, like, ‘Oh, I disagree with him on this one education plan he has.’ ”

Democrats who are hoping Pelosi takes a more active role are not looking for an endorsement but rather would like her to be a power broker in uniting the support now fragmented among more moderate candidates like Biden, former New York mayor Mike Bloomberg, Buttigieg and Sen. Amy Klobuchar (D-Minn.).

“It’s more of an effort to try and go to some of the more moderate candidates and see if they can kind of coalesce behind someone and make a deal,” said one centrist Democratic lawmaker, who spoke on the condition of anonymity to describe private discussions. “There’s a lot of influential people in the party, gray-haired eminences, who could have some sort of role.”

Rep. Don Beyer (D-Va.), a But­tigieg supporter, said Pelosi was one of the only Democrats in the country — alongside former president Barack Obama — who would have the stature to play that role. But, he quickly added, “There’s no indication either one of them wants to play that role right now.”

“She certainly has the gravitas, the wisdom, the acute sense of strategy to do something like that,” Beyer said.

Asked Wednesday about whether she thought she had the power to help cull the field, Pelosi said, “The power is with the people.”

That sentiment is shared with many moderates, who fear a repeat of 2016 — when Sanders supporters were left smarting after the Democratic National Committee appeared to tilt the playing field toward eventual nominee Hillary Clinton. Some have blamed the hard feelings for Clinton’s eventual loss to Trump.

Rep. Darren Soto (D-Fla.), who represents a central Florida district and sharply criticized Sanders’s recent Cuba comments, said any coordinated effort among the party leadership “would have the exact opposite of the desired effect” on the electorate.

“We saw an attempt to stack the deck in 2016, and that did not work so well,” he said. “Let the voters decide. Let it roll.”

Shalala, too, said it was up to voters — not Pelosi — to speak out: “They know who he is. They know what he said. They know he’s wrong. And they have to speak.”