Seven years of budget headaches ended for President Obama on Tuesday, when he sent Congress his seventh and final spending plan. But this year’s fiscal fights are just beginning for Republicans on Capitol Hill.

GOP leaders have already announced they will ignore the White House budget rather than engage in another round of brinksmanship with the president. In an unusual move, they broke with a four-decade tradition and declined to invite Office of Management and Budget Director Shaun Donovan to give his customary testimony on the spending proposal.

[Budget breakdown: What the White House wants to spend money on]

“This isn’t even a budget so much as it is a progressive manual for growing the federal government at the expense of hardworking Americans,” House Speaker Paul D. Ryan (R-Wis.) said of Obama’s proposal.

But Republicans have their own problems to worry about.

Republican leaders are facing another conservative uprising over spending that is threatening to derail the two-year budget compromise crafted last year with Obama and congressional Democrats. The spending standoff will test Ryan’s promise to bring regular order — passing a budget, then spending bills — and good governance back to a chronically gridlocked Congress.

[Obama’s final budget proposal calls for an almost 5 percent spending boost]

Both Ryan and Senate Majority Leader Mitch McConnell (R-Ky.) have highlighted moving spending bills through Congress as a major aspect of their 2016 agenda ahead of the November election — and not much else.

But in a reprise of past budget battles, the same group of conservative hard-liners that have held GOP leaders hostage to their demands in past Congresses is threatening to rebel over a $30 billion spending increase approved as part of then-Speaker John Boehner’s (R-Ohio) last act.

Some conservatives are looking to the new speaker to resurrect the controversial budget blueprints Ryan drafted when he was House Budget Committee chairman, which would have balanced the government’s books by 2025.

“Why would you vote against the [2015] budget deal, against the omnibus and then vote for this new budget that reinforces the things you already voted against?” asked Rep. Mick Mulvaney (R-S.C.).

The problem is this: the first step in the promised regular order is passing a budget, and Ryan needs conservative support to get that done.

Stalwart conservatives — many of them members of the House Freedom Caucus — are threatening to reject any budget that adheres to the Boehner-era spending agreement. Ryan can only afford to lose 28 Republican votes, and many hard-liners have already threatened to defect.

Freedom Caucus chairman Jim Jordan (R-Ohio) said Tuesday that last year’s fiscal compromise is already expected to add $105 billion to the deficit over the next decade, according to the Congressional Budget Office. That leaves conservatives with no choice but to vote against any new spending.

“Let’s do a budget that reflects the environment we find ourselves in,” Jordan said. “There might be an agreement that [former] Speaker Boehner and Obama got last fall but there have been new variables added to the equation.”

[House Republicans are having a ‘family conversation’ on budget]

The idea of compromise has been a non-starter for outside groups that hold significant sway in conservative circles. Heritage Action, perhaps the most influential of those groups, released a memo Tuesday condemning any talk of supporting the Boehner-era budget numbers.

“To be clear, there is absolutely no conservative reason to support a Republican budget at spending levels dictated by Barack Obama and congressional Democrats,” the memo read.

The Heritage Action memo encouraged members not to be enticed by “unenforceable promises” of regular order or the prospect of using budget rules to skirt a Senate filibuster and force votes on repealing Obamacare or cutting Social Security spending. Those rules, the memo said, could be just as easily used to pass “establishment” priorities in a lame-duck session.

Unlike in the House, McConnell’s biggest challenge is negotiating with Democrats, not members of his own party. “I support what we did last year and we are going to do everything that we can to maintain that,” Senate Minority Leader Harry Reid (D-Nev.) said Tuesday.

Regular order has proved difficult to achieve in recent years. Congress has only completed the full budget and appropriations process on time four times since 1977. The task is even more challenging in an election year when many members want to avoid fights that could scare off voters. Spending bills are typically magnets for politically touchy issues, including abortion rights, gun control, immigration and foreign policy.

Budget experts say Republican leaders are now trapped between promises to uphold regular order and unrealistic expectations. Many of the party’s most conservative members suppport controversial policy documents that will be impossible to enact in a divided government — recent GOP budgets, like Ryan’s 2014 Path to Prosperity, repealed the Affordable Care Act and scaled back Medicare to help balance the books.

“I think one of the things that made this politically impossible was picking fiscally impossible goals,” said Maya MacGuineas, president of the bipartisan Committee for a Responsible Federal Budget.

MacGuineas said Ryan’s balanced budgets  were always ambitious, but ensuring the federal government’s ends meet has grown increasingly unlikely.

Discretionary spending under the annual appropriations process only covers about one-third of the overall federal budget. The other two-thirds comes from mandatory programs, like Social Security, Medicare and Medicaid, that are growing far more rapidly. Those programs, combined with recently enacted tax cuts, are expected to add $105 billion to the deficit this year, according to the Congressional Budget Office.

[Budget deficit set to rise thanks to year-end tax deal]

Republican leaders say they expect to stick to last year’s deal, and Ryan has downplayed the severity of the party infighting.

So far, Ryan’s solution has been to let members share their concerns, offer suggestions for how to compromise by cutting spending elsewhere and generally give members a chance to vent. Last week, he met with Freedom Caucus members and he plans to continue those talks throughout the week. The speaker will attend budget meetings held by House Majority Whip Steve Scalise (R-La.)  and will wrap up the week with a Friday planning conference with all Republicans.

[In address, Paul Ryan pledges a ‘complete alternative’ to the Democratic agenda]

Lawmakers also have a shorter than usual timeframe to finish the budget process this year. Congress has until Sept. 30 to pass spending bills, but the November election has forced a shorter-than-usual session.

Both houses are scheduled to leave Washington in mid-July to attend party nominating conventions, and they will return only briefly in September before an extended recess for campaigning.

That means if the budget process gets bogged down in the coming weeks, it will become increasingly likely that congressional leaders will forego “regular order” and instead pass a stopgap extension of current funding levels.

Mike DeBonis contributed to this report.