Speaker of the House Paul D. Ryan (R-Wis.) speaks to the media following the House Republican conference meeting on Capitol Hill on Feb. 14, 2017, in Washington. (Pete Marovich/For The Washington Post)

House Speaker Paul D. Ryan (R-Wis.) spent Tuesday on a door-to-door tour of the Capitol in hopes of salvaging his plan to repeal and largely replace the Affordable Care Act by spring.

The day-long blitz comes as Republicans in Congress have made virtually no visible progress in recent weeks on overhauling the health-care system, according to interviews with several senior GOP aides.

That is largely because the party remains sharply divided over how much of the ACA should be repealed and how much — if any of it — should be replaced. The stalemate has lawmakers questioning whether the law known as Obamacare can be effectively gutted by Ryan’s self-imposed deadline of the end of March.

“I don’t think you can fully repeal and replace it in that amount of time,” said Rep. Tom Cole (R-Okla.). “It took months to write Obamacare, the original bill, and years to phase it in. It is going to take time to unwrite it and replace it with something else.”

Ryan’s efforts are being stymied by a host of factors, including a familiar revolt from his most conservative members, who want to keep their promises to eliminate Obamacare regardless of the pace of a replacement measure. Meanwhile, Senate Republicans are not ready to act on any kind of repeal without a consensus replacement plan. The Washington infighting is playing out against a backdrop of rowdy GOP town halls across the country showcasing people worried about the impact on their lives of potentially losing their health insurance.

For Ryan, the stakes could not be higher. While trying to satisfy his right flank, the speaker also must consider the potentially explosive impact of the health-care debate on his quest to maintain and grow the GOP majority in the 2018 midterm elections. Further confusing things is President Trump, who has both vowed to repeal and replace the ACA immediately, and said that such a process would take until 2018.

Dozens of GOP members attended an afternoon briefing Tuesday on Medicaid. The issue is one of the biggest sticking points among Republicans, opening divides between lawmakers in states who have accepted the program’s expansion under Obamacare and those who have opted out, forgoing hundreds of millions of federal dollars a year in protest against the law.

Inside the closed-door sessions, senior lawmakers walked through a variety of options for replacement — including a radical reorientation of the Medicaid program, an open-ended insurance entitlement and a fixed “block grant” that would let states decide how to apportion health-care dollars for the needy. They also considered an indefinite extension of the ACA Medicaid expansion that would allow those now covered to remain so.

“They got to see a lot of the details of the plans that we’re working on,” said House Majority Whip Steve Scalise (R-La.), who hosted the session. He added, “There’s a lot of work left to be done.”

Republican senators who represent states that expanded Medicaid — including Bill Cassidy (La.), Rob Portman (Ohio) and Lisa Murkowski (Alaska) — huddled last week to discuss concerns that a House GOP repeal bill could leave millions of their constituents without insurance. While no consensus emerged, many lawmakers said they could not support an aggressive repeal bill that could harm so many of their constituents.

“We’ve added 27,000-some-odd Alaskans to the covered rolls,” Murkowski said Tuesday. “I want to make sure whatever we do post-ACA, we don’t leave these good folks hanging.”

The debate is playing out against a backdrop in which the proportion of Americans without health insurance through most of last year remained at the same low level as in 2015, according to survey data released Tuesday by the National Center for Health Statistics. The data, covering January through September 2016, showed that 8.8 percent of people of all ages were uninsured compared to the 9.1 percent uninsured through 2015, according to the U.S. Census’s most recent annual report on health insurance rates.

It is unclear how much of that improvement is the result of an improving economy and how much was brought about by the ACA’s impact. Meanwhile, the insurer Humana announced it would stop selling individual plans under the ACA after this year.

On Capitol Hill, Republicans are locked in a battle for control over the repeal process. Conservatives are seeking to reassert their influence after several weeks where more-moderate lawmakers — and Trump himself — have seemingly argued for a more deliberate process.

Members of the hard-right House Freedom Caucus and conservative Republican Study Committee are insisting that a repeal bill should go at least as far as a measure they approved in 2015. That bill ended with a veto from President Obama, but GOP leaders touted it as a test run for what could be possible with a Republican president.

“What we’re trying to do is really create some urgency,” said Rep. Mark Walker (R-N.C.), chairman of the Republican Study Committee. “We’re okay with talking through that and hearing what they [House leaders] have for us, but ultimately, we’ve promised to the American people that we’re going to get this thing off the books as quick as possible. That’s what we’re asking the leadership to do.”

Leaders are using a quirk in the budget process to repeal Obamacare without the threat of a blockade by Senate Democrats.

Budget legislation is considered under special rules in the Senate that allow a simple majority of 50 senators to support passage rather than the normal 60 needed for almost everything else. While there are 52 Republicans in the Senate, some of them are unlikely to support a rapid repeal without a replacement in place.

Ryan set out Tuesday to rally the GOP to consensus, starting the day by launching several policy sessions to offer rank-and-file members some details of what could be included in the replacement plan. He outlined several common ideas that unite the GOP, such as expanding health savings accounts and allowing insurers to sell plans across state lines. He also announced plans for a Thursday meeting where members will be briefed on further details just before they leave for a week-long recess where many plan to hold events with constituents.

Ryan told reporters after the meeting that the plan for a “step-by-step” process to replace ACA was still on track.

“We have to stop the collapse, and we have better ideas that have been time-tested that will make sure that we give the American people the kind of relief they deserve,” Ryan said.

He then headed to a closed-door lunch in the Senate where he pitched the outlines of his vision for replacement.

But Republicans largely left the meetings unable to identify any specific proposals that go beyond a small number of general ideas. “There was a lack of specificity,” Cassidy said after the meeting. “Ideas are bubbling together.”

The conversation was not as specific as would be expected at this point in a major policy negotiation, according to several GOP aides. One aide described the talks as remaining in “the very beginning stages.”

Carolyn Y. Johnson contributed to this report.