President Donald Trump made the American people a promise over and over again: His administration would not touch Social Security and Medicare funding.

Then Trump’s budget proposal to Congress included cuts to Social Security Disability Insurance. Now congressional Republicans, who have begun debating the actual budget, are putting Medicare on the table too — a major break from Trump, and yet another indication of how little the president dictates conversation on Capitol Hill.

Republican Rep. Tom Cole of Oklahoma, who sits on the House Budget Committee and is the chair of the appropriations subcommittee that manages health spending, said this week that Republicans aren’t going to let what the president campaigned on affect what they have been working toward for years. Trump’s promise to leave Medicare and Social Security as is and balance the budget is a “fantasy,” he said.

“We have been talking about Medicare and Medicaid reform all the way through,” Cole told Vox Monday. “I’m not asking the president to abandon his principles. He is the president of the United States. He doesn’t have to sign something. But we shouldn’t abandon ours either.”

Cole continued:

Just because they have a political construct that they ran on — with all due respect, if you are not willing to tackle Social Security, Medicaid, and Medicare, you are not ever getting a balanced budget, and to pretend otherwise is a fantasy. I would hope we could craft a more serious proposal than that, and the best way to do that is sticking with some of the things we have the votes to do. People have cast those votes [on Medicare] before. I wouldn’t give up any of the places where we have been aggressive in the past.

Cole is hinting at what will inevitably be a difficult road ahead for Republicans on budget negotiations, which almost always pass on party lines. Last year, Republicans failed to pass a real budget, and this year the party remains just as divided. There are defense hawks, budget hawks, and spending appropriators who are used to bipartisan negotiations, all of which have different priorities.

This year, the stakes are even higher: If Republicans can’t agree to a budget resolution, they can’t move to tax reform — at least not in the way they would like. It’s becoming increasingly clear that they aren’t going to let Trump’s campaign promises be yet another limitation.

Republicans will have to mend a lot of divisions to pass a budget

In what would undoubtedly be a major break from Trump’s campaign promises, the House’s budget proposal is expected to include some changes to Medicare, which House Speaker Paul Ryan has long championed, according to the New York Times.

Cole is right that Republicans are going to need all the votes they can get to pass a 2018 budget, given how wide the divisions are in the party. There’s overwhelming agreement among Republicans to increase spending on defense, but there’s resistance among party moderates to offset those spending hikes with cuts to domestic programs. And conservatives in the House, which control more than enough votes to tank a budget resolution on the floor, have already said there will need to be cuts in spending elsewhere in order to win their votes. Conservative Rep. Jim Jordan (R-OH) has proposed attached welfare reform to tax reform in the budget resolution.

Top Republicans, like Rep. Kevin Brady of Texas, don’t seem too keen on the idea, claiming tax reform is hard enough as is. But if conservatives hold their ground, House leadership might not have a choice — even knowing that it will likely pose a major problem for the moderate voices in the Senate.

If welfare reform is what helps solve the internal problems to actually do a budget, Cole said he could swallow tougher numbers. Even so, he’s keeping expectations low.

“There is no certainty because we failed last year,” Cole said. “It’s easy to fail two years in a row. It’s like when you fall off your diet or something — it’s really hard to get back after those sundaes that are great, and five burgers a night are wonderful.”

Congress could break Trump’s promise, and he doesn’t have much leverage to stop it

Budget resolutions do not require a president’s signature, nor do they allow for executive veto power. Usually the president’s budget proposal sets a vision for the party going into negotiations.

But top Republicans in Congress took Trump’s budget seriously but not literally. They called it “symbolic,” and an idea to consider — knowing all too well that they would have to thread the needle between tax cutters, deficit hawks, and defense hawks.

Cole said Trump’s budget lost the White House leverage in negotiations on Capitol Hill simply because the numbers didn’t add up.

“It’s not like [Office of Management and Budget Director Mick] Mulvaney hasn’t been up here pushing, but they don’t have a budget that Mick would have ever voted for in my view,” Cole said. “I don’t think they are in a strong position here. This is something we need to sort out amongst ourselves.”

The legislative calendar will force a showdown among Republicans, who early on set an ambitious agenda to tackle both health care and tax reform before the fiscal year’s end on September 30. Budget Committee members have said they plan to propose budget resolutions sometime in June, but so far movement only seems to be happening in the House.

Sen. Bob Corker (R-TN), who sits on the Senate Budget Committee, summed up the status of talks in the upper chamber succinctly last week: “I don’t know anything about it,” he said in early June. “I’m on the Budget Committee and I don’t know.”