Republicans are openly feuding over whether to seek drastic changes to Medicare, Social Security and other entitlement programs, risking a potentially damaging intraparty battle ahead of the 2016 elections.

The rift was exemplified this week by the GOP stars of the moment. Newly installed House Speaker Paul D. Ryan (R-Wis.) said he plans to pursue a “bold alternative agenda” that would include major revisions in entitlements. At the same time, leading Republican presidential candidate Donald Trump railed against proposals to end or significantly change Medicare.

The dispute is part of a larger GOP argument over which policies Republicans will present to voters next year and how far the party should go in pushing for changes. Three years ago, GOP presidential nominee Mitt Romney and Ryan, his running mate, faced withering Democratic attacks after endorsing dramatic overhauls of Medicare and Social Security that proved unpopular.

The Republican presidential candidates are jockeying to be seen as in solidarity with Ryan, the darling of party elders, or with Trump, a voice for grass-roots voters.

“This is the biggest fault line in the party: whether Republicans should be talking about reducing benefits,” conservative economist Stephen Moore said in an interview. “Republicans have fallen on their sword for 30 years trying to reform Social Security and Medicare, but the dream lives on — and it makes everyone nervous. Some see a political trap; others see it as necessary.”

As Medicare turns fifty, the politics of the plan are as hotly contested as ever. For Republicans, it's created a wedge among the presidential candidates. (Pamela Kirkland/The Washington Post)

For years, Ryan has embraced proposals that would privatize parts of Social Security, slash Medicaid and convert Medicare to a voucher-based program, in which private insurance would be purchased with federal subsidies. His vow to try again as House speaker quickly earned the attention of top Democrats, who are eager to revive criticisms they’ve used against Ryan and other Republicans in the past.

In Iowa on Tuesday, Democratic front-runner Hillary Rodham Clinton called GOP attempts to remake Social Security and Medicare “a terrible idea.”

“Talk about giveaways to Wall Street — this would be the biggest giveaway ever,” she said of Ryan’s plans.

And Rep. Debbie Wasserman Schultz (Fla.), who chairs the Democratic National Committee, used a speech to Florida Democrats over the weekend to blast former Florida governor Jeb Bush and Sen. Marco Rubio (R-Fla.) for backing Ryan’s “recycled” ideas on revamping Medicare.

Ryan said this week that one of his priorities will be taking “en­titlements off of the collision course they’re on with the rest of the budget.”

He later added: “We’re not going to worry about who is doing what in the presidential election.”

House Speaker Paul D. Ryan (R-Wis.) gestures on Capitol Hill in Washington. Ryan has vowed to seek major changes to entitlement programs. (Andrew Harnik/AP)

Trump and other populist contenders, including former Arkansas governor Mike Huckabee, have challenged the need for sweeping changes and have warned against riling the seniors who have become a crucial voting bloc. This week, Trump attacked emerging front-runner Ben Carson — his main GOP rival — for advocating reforms to Medicare.

“Ben wants to get rid of Medicare,” Trump said during a news conference at Trump Tower in New York on Tuesday. “You can’t get rid of Medicare. It’d be a horrible thing to get rid of. It actually works. You get rid of the fraud, waste and abuse — it works.”

Carson had previously said he wanted to replace Medicare with a system of health savings accounts for seniors but now says he would give them the option of keeping traditional Medicare if they prefer.

Huckabee, who places far behind Trump and Carson in polling, has earned attention in recent debates for describing plans to revamp Medicare and Social Security as “theft.” He proposes driving down costs by rooting out cases of entitlement fraud and abuse.

“People are sick of believing that the government is never going to really address this,” Huckabee said in last week’s CNBC debate in Colorado. “But let me tell you who not to blame. Let’s quit blaming the people on Social Security. Let’s quit making it a problem for them. It’s like them getting mugged and then us saying, ‘Well, we’re going to mug you some more.’ ”

Other GOP presidential candidates have introduced detailed plans to overhaul Social Security and Medicare that are more in line with Ryan’s thinking.

On Social Security, Bush says he would “encourage private saving to reduce dependency on the government” and has adopted proposals supported by House Republicans and the bipartisan Simpson-Bowles fiscal commission. Bush would gradually raise the retirement age for full benefits by a month each year beginning in 2022, when the retirement age is already set to become 67. The retirement age would rise to 68 by 2034 and to 69 by 2046.

New Jersey Gov. Chris Christie is in effect running on fiscal change, casting himself as a truth-teller to audiences in New Hampshire and Iowa. Like Bush, Christie would make changes in the age of eligibility and backs means-testing for both programs. But he would slash Social Security benefits for Americans earning more than $80,000 annually and end them entirely for people earning more than $200,000.

Rubio, who has been moving up in recent polls, has said he supports means-testing and changing the eligibility requirements for future beneficiaries but has not released detailed plans.

Robert L. Bixby, executive director of the Concord Coalition, a nonpartisan fiscal policy group that favors revamping, said Bush and Christie have “realistic plans in both cases. Those are the kinds of changes we’re going to have to be dealing with. But we’re also going to add some revenue to the mix. I don’t think it’s politically feasible to pass any kind of entitlement reform that does everything on the benefits side.”

Moore urged Republicans to proceed with caution as they debate entitlement programs.

“How many times do Democrats have to run ads of Granny getting pushed off of a cliff in order for Republicans to see that making this their main issue isn’t politically practical?” he said. “It may be shocking, but Trump seems to have grasped that. Republicans should be fighting not about giving less but about economic growth. That’s the better turf for the party to play on.”

But William J. Bennett, a former education secretary and a Ryan confidant, said the new speaker is likely to proceed with his proposed changes regardless of presidential politics.

“Paul has been very strong on this and isn’t going to budge,” Bennett said. “He’ll be aggressive if he needs to — with the administration or with a candidate. He’s his own man. It’s just crazy to think they shouldn’t be reformed.”

Generally, there is a class split among Republicans over whether to reduce spending on entitlement programs. Polling of Republicans conducted in the past several years by the Pew Research Center showed that party supporters without college degrees are more supportive of maintaining Social Security and Medicare benefits, while college graduates are more supportive of cutbacks.

Trump has shrugged off Ryan’s proposals as political missteps. “He’s been so anti-Medicare, Medicaid, Social Security, in a sense,” Trump said of Ryan last month on CBS’s “Face the Nation.” “Now, he would say he hasn’t been, but [Democrats] certainly played that up hard” in the 2012 race.

Ryan has been muted in response. Asked Sunday on ABC’s “This Week” whether he could support Trump as the GOP nominee, Ryan said the mogul would be better than Clinton.

“We’re having a good primary process,” he said. “It’s cathartic, it’s helpful.”

Scott Clement contributed to this report.