While the situation with Syria is getting more fluid by the hour, the next step in the other morass confronting Congress is getting clearer: A truce in the budget wars is going to be declared until the holidays.

Mark your calendars with Dec. 15, two Sundays before Christmas, as the new target adjournment date for the first session of the 113th Congress.

Republican leaders will unveil legislation this afternoon, which the House will debate by Thursday, that would continue appropriations to all agencies and departments flowing at current, trimmed-by-the-spring-sequester levels for the first 75 days of fiscal 2014, which starts Oct. 1.

The status quo spending levels was chosen as the obvious middle ground between the most conservative Republicans, who would like to impose deeper cuts on domestic if not military programs, and mainstream Democrats, who aspire to turn off the sequester altogether.

Since neither of those approaches has any chance of passing the House, GOP leaders are banking that the short-term, running-in-place approach can be sold — as the only viable option — to bare majorities of both their own caucus and the Democrats. Such a straightforward continuing resolution would likely command a strong bipartisan majority in the Senate.

Whether the CR will be the venue for a climatic fight over the future of Obamacare has been one of the big mysteries of the summer. But Republican leaders believe they have found a way to finesse the situation, making the spending bill’s path less complicated without infuriating too many conservatives. The latter say the government should be shut down at the end of the month unless President Barack Obama agrees to effectively repeal his most significant legislative achievement.

Speaker John A. Boehner and Majority Leader Eric Cantor will sell the plan to their caucus this afternoon.

Here’s legislative maneuver they envision: Before considering the CR, the House would debate — and presumably pass with Republican votes — separate legislation that would stop all federal spending to implement the 2010 health care law. That bill would go to the Senate with some kind of “self-executing” rule that would hold back the clean CR until the Senate votes on the defunding bill.

The notion is that, while a majority of senators would reject the defunding measure, they would all be forced to go on record on the question. Republicans are eager to see that happen to make political life more difficult for a handful of Senate Democratic centrists seeking re-election next year.

Not everyone thinks this two-step is such a great plan. The Club for Growth is the most influential conservative advocacy group that has come out against it, insisting that GOP leaders press ahead in holding all federal funding hostage to the Obamacare repeal.

But GOP leaders seemed convinced of their scheme’s merit. “The House has taken a stand numerous times on its opinion of Obamacare,” Cantor told reporters Tuesday morning. “It’s time for the Senate to stand up and tell their constituents where they stand on this atrocity of a law.”

All this is happening against a backdrop of an improving federal balance sheet. Declining federal spending because of the sequester, and rising revenue because of the improving economy, means the federal deficit for all of this year should come in below $750 billion, which would be the smallest amount of red ink in five years, the Congressional Budget Office estimated Monday.

If the truce plays out and House and Senate meet the Dec. 15 adjournment mark, it will be their earliest finish in a non-election year since 2003, which wrapped up one week earlier.