House conservatives are pushing to subvert a budget agreement being negotiated by Rep. Paul Ryan (R-WI) and Sen. Patty Murray (D-WA) that would mitigate some of the painful sequester cuts and remove the threats of government shutdown.

A letter signed by at least 18 conservative Republicans urges Speaker John Boehner (R-OH) to bring up a “clean” continuing resolution (CR) to fund the government at the low sequester level when money expires on Jan. 15. The GOP signatories insist they want to avoid another confrontation and argue that Democrats would be responsible for a shutdown if they refuse to keep spending at levels established under current law.

“The Budget Control Act is the law of the land,” the lawmakers write. “Our Democrat colleagues are now threatening to shut the government down in order to change that. We should not permit that to happen. Again, we encourage you to bring a clean CR to the floor.”

The sequester orders 2014 spending at $967 billion — hardline conservatives don’t want to spend a penny more than that. Ryan and Murray are close to a deal that raises spending to about $1 trillion. Democrats roundly oppose sequester spending levels and many Republicans, especially defense hawks, want to ease the cuts because they believe they’re unsustainable and damaging to national security. House Republican leaders support the Ryan-Murray framework but are often at the mercy of their right flank.

“We recognize that a clean CR would preserve the cuts called for in the sequester,” the letter reads. “We are very much aware that these cuts are inefficiently applied, and that they impact the military disproportionately. For that reason we have supported numerous efforts to either replace the sequester or to allow flexibility in its implementation. It is not lost on us, however, that the Democrats have opposed all of those efforts.”

The letter was spearheaded by Reps. Mick Mulvaney (R-SC), Jim Jordan (R-OH) and Steve Scalise (R-LA). It began circulating Thursday, and a Republican aide said the members will continue to gather signatures until Monday. It’s an uphill battle for conservatives this time, given broad opposition to the sequester, but the members who signed the letter are the types who have called the shots in the chamber for the last three years.

House GOP leaders are eying a vote this month on a clean CR as a fallback option in case the Ryan-Murray talks collapse. Boehner is keeping his powder dry — for now. “I’m hopeful that Chairman Ryan and Senator Murray would be able to come to an agreement,” the Speaker said Thursday. “I haven’t seen the agreement. We’ll wait and see what it looks like.”

Meanwhile, House Democrats also dislike the framework of the Ryan-Murray talks. They’re not likely to scuttle a deal but they want to move the needle leftward. They believe the emerging agreement, as reported by TPM and others, is lopsided in favor of special interests and against working families. They’re upset that it’s unlikely to extend emergency unemployment insurance and they’re unhappy that it won’t close any tax loopholes.

Notably, House Minority Whip Steny Hoyer and Budget Committee Ranking Member Chris Van Hollen, both Maryland Democrats, are troubled by rumors that the Ryan-Murray deal may cut some $20 billion from federal employee pensions, according to sources familiar with their thinking. If such a provision makes it into a final budget deal, they might vote against it and refuse to persuade colleagues to vote for it.

In an effort to influence the debate, Van Hollen released his own budget proposal Thursday that he said reflects Democrats’ principles. Part of the aim is to give Murray leverage. “They’re going to need House Democratic votes to get a deal done and passed,” said a senior House Democratic aide. “And the deal has to represent our values and priorities.”

Van Hollen said the “budget conference negotiations have dragged on for too long and left important priorities at risk. … House Democrats believe we must reduce the deficit, but we cannot ask working families to shoulder that burden alone. We will continue to fight for these key provisions as part of the budget negotiations.”

If a budget deal is reached by the Dec. 13 conference deadline, the biggest challenge will be selling conservatives — particularly the ones who signed the letter to Boehner demanding a sequester-level continuing resolution. Outside groups like Heritage Action and Club For Growth could have a major influence on whether the deal passes the House. Spokesmen for the two groups declined to comment on the Ryan-Murray framework for this article.

If a deal falls apart, the odds of another government shutdown increase dramatically come Jan. 15. But even if a deal is reached, Congress is far from home, as it will have just one month to flesh out and pass appropriations bills. “I think even if Murray and Ryan come to an agreement,” said a second top House Democratic aide, “it is miles and lots of moving pieces between that and enactment of an omnibus [spending bill] by Jan. 15.”

GOP Letter to Leadership on Sequester-Level CR