WASHINGTON — House Republican leaders and the White House, under extreme pressure from conservative activists, have restarted negotiations on legislation to repeal the Affordable Care Act, with House leaders declaring that Democrats were celebrating the law’s survival prematurely.

Just days after President Trump said he was moving on to other issues, senior White House officials are now saying they have hope that they can still score the kind of big legislative victory that has so far eluded Trump. Vice President Mike Pence was dispatched to Capitol Hill on Tuesday for lunchtime talks.

“We’re not going to retrench into our corners or put up dividing lines,’’ House Speaker Paul D. Ryan said after a meeting of House Republicans that was dominated by a discussion of how to restart the health negotiations. “There’s too much at stake to get bogged down in all of that.’’

The House GOP whip, Steve Scalise of Louisiana, said of Democrats, “Their celebration is premature. We are closer to repealing Obamacare than we ever have been before.’’

It is not clear what political dynamics might have changed since Friday, when a coalition of hard-line conservatives and more moderate Republicans torpedoed legislation to repeal President Barack Obama’s signature domestic achievement. The replacement bill would still leave 24 million more Americans without insurance after a decade, a major worry for moderate Republicans. It would also leave in place regulations on the health insurance industry that conservatives find anathema.

Ryan declined to say what might be in the next version of the Republicans’ repeal bill, nor would he sketch any schedule for action. But he said Congress needed to act because insurers were developing the premiums and benefit packages for health plans they would offer in 2018, with review by federal and state officials beginning soon.

The new talks, which have been going on quietly this week, involve Stephen K. Bannon, the president’s chief strategist, and members of the two Republican factions that helped sink the bill last week, the hard-right Freedom Caucus and the more centrist Tuesday Group.

Any deal would require overcoming significant differences about how to rework a law that covers about one-fifth of the US economy, differences that were so sharp they led Trump and Ryan to pull the bill from consideration just as the House was due to vote Friday.

Still, Republican members of Congress said they hoped that revisiting the issue would lead this time to a solution and a vote in the House.

“I think everyone wants to get to yes and support President Trump,’’ said Reresentative Dave Brat, a Virginia Republican and Freedom Caucus member. “There is a package in there that is a win-win.’’

Representative Raúl Labrador of Idaho, another Freedom Caucus member, hoped the discussions would yield a compromise that brings the party together after a divisive debate that revealed deep fissures. “I think we will have a better, stronger product that will unify the conference,’’ he said.

Trump has sent mixed signals in recent days, at times blaming the Freedom Caucus, outside groups and even, it appeared, Ryan. On Monday, for instance, he said in a late-night Twitter post that the Freedom Caucus was able to “snatch defeat from the jaws of victory’’ over the health care repeal. “After so many bad years they were ready for a win!’’

But then he suggested that he could also cut a deal with Democrats, a move that would almost certainly make more conservative members of the House balk. “Don’t worry,’’ he tweeted later Monday night, “we are in very good shape!’’

Ryan said House Republicans were determined to use the next version of the repeal bill, like the first version, as a vehicle to cut off federal funds for Planned Parenthood clinics.

Asked if he saw any signs that members of the conservative House Freedom Caucus might be willing to compromise, he said: “I don’t want us to become a factionalized majority. I want us to become a unified majority, and that means we’re going to sit down and talk things out until we get there, and that’s exactly what we’re doing.’’