Updated: 9:56 p.m.

Attempts to wrap up a bitterly contentious session of Congress fell into disarray Tuesday as Republicans vowed to filibuster a one-year spending bill and Democratic infighting threatened to sink the White House’s tax cut deal.

By late Tuesday night, the only thing that seemed certain was that Congress will, for the second year in a row, be in session the week of Christmas.

But even the end date continued to slip further into the future as Majority Leader Harry Reid raised the possibility of a post-Christmas — and potentially post-New Year’s — session to finish work on taxes, the Strategic Arms Reduction Treaty, the repeal of a ban on openly gay service members, immigration reform and even a public lands bill.

“There’s still Congress after Christmas. We’re not through,” the Nevada Democrat told reporters Tuesday, warning the session could extend into the new year. “Congress ends on Jan. 4.”

Reid’s schedule drew a strong and religiously charged rebuke from Minority Whip Jon Kyl.

“It is impossible to do all of the things that the Majority Leader laid out without doing — frankly, without disrespecting the institution and without disrespecting one of the two holiest of holidays for Christians and the families of all of the Senate, not just the Senators themselves but all of the staff,” Kyl said Tuesday.

GOP anger wasn’t limited to the schedule, as leaders lashed out at Democrats’ proposal for a massive omnibus spending bill, carrying thousands of earmarks worth billions of dollars. Appropriations Chairman Daniel Inouye (D-Hawaii) offered the bill as an alternative to the yearlong continuing resolution passed by the House last week.

“I am actively working to defeat it,” Senate Minority Leader Mitch McConnell said of the omnibus bill released Tuesday. “It is completely and totally inappropriate to wrap all of this up into a 2,000-page bill and try to pass it the week before Christmas.”

The Kentucky Republican’s opposition comes despite the fact that he — and other Republicans — would garner millions of dollars in earmarks in the bill. For instance, the bill includes $3 million in funding for the Fort Campbell “Shoot House,” $1 million for a Kentucky Blood Center Building and $1 million for the Paducah Waterfront Development Project. All of those items were requested earlier this year by McConnell.

McConnell brushed aside questions about his earmarks, arguing that while he had sought the funding, he would oppose the bill because of how Reid brought it to the floor.

“I’m going to vote against things that arguably would benefit my state. I do not think this is the appropriate way to run the Senate,” he said.

The omnibus bill will also face a multipronged filibuster from Republicans along with other tactics intended to slow it down or kill it.

“Democrats haven’t given Republicans or the American people time to read the bill, but I’ll join with other Republican colleagues to force them to read it on the Senate floor,” Sen. Jim DeMint (S.C.) said Tuesday.

Additionally, while Democratic leadership aides said Reid’s strategy hinged in part on getting GOP appropriators to vote for the bill, McConnell indicated that might not happen.

“I’m vigorously in opposition to it. And most of the members of the committee are as well,” he said. If GOP appropriators do oppose the bill, it could make it impossible for Reid to break Republicans’ filibuster.

In the House, a strategy to wrap up work for the year remained in a holding pattern Tuesday as Democratic leaders struggled to find a way forward on the tax measure.

Democratic leaders huddled privately for more than two hours Tuesday afternoon to plot an endgame strategy but did not emerge with a clear path forward.

“We’re considering options, and we’re going to talk to the Caucus about that,” Rep. Chris Van Hollen (D-Md.) said. “We may be making some proposed recommendations and then they’ll have an opportunity to debate them, discuss them … We’ll receive input from the Caucus and then figure out where to go from there.”

The Democratic Caucus, which was slated to meet after press time, was also expected to consider a resolution proposed by Rep. David Wu (Ore.) stipulating that the House would only consider legislation that would extend unemployment benefits at least as long as it extends tax cuts for the wealthy. However, Wu withdrew his resolution at the request of Caucus Chairman John Larson (D-Conn.).

Rules Chairwoman Louise Slaughter said there would likely be at least a few amendments made in order to the bill.

Any changes made in the House would require that the bill be sent back to the Senate for another vote.

Slaughter predicted that there would be a vote “of some kind” on the Senate package but declined to speculate further. “We’ll be prepared when the time comes,” the New York Democrat said.

Democratic leaders have indicated that they may try to change — or at least give Members a chance to register opposition to — the Senate’s estate tax language, which would impose a 35 percent tax on estates worth more than $5 million. Majority Leader Steny Hoyer acknowledged Tuesday that House leaders could try to replace that provision with House-passed imposing a 45 percent tax on estates worth more than $3.5 million.

Blue Dog Coalition leaders were circulating a letter to Pelosi on Tuesday night asking her to quickly schedule a vote on the Senate tax bill ­­— without changes — once it is sent over.

Hoyer left open the possibility that the House could work the weekend — or into next week — to finish its work for the year.

But the Maryland Democrat conceded that House leaders were “going to have to make a decision pretty soon” on how to proceed with tax cuts, given the fast-approaching Christmas holiday.

“I haven’t even put up my tree, much less decorated it,” he joked. “I tell you what, I’m getting worried.”

But some House Democrats appeared to be recognizing that efforts to change the bill could just delay an inevitable vote on the Senate language. One senior Democratic aide predicted that even if the House did adopt changes, the Senate would just send back its original version of the measure, leaving the House with little choice but to pass it.

“I think everybody knows what the endgame is,” the senior aide said. “It’s no secret. Inevitably, we will pass the clean Senate package. It’s just if it is this week or next week.”

Given that reality, the aide predicted that the House could pass the Senate language unchanged in the first go-round.

“Once Members think about that and look at the calendar, the odds increase greatly that they will defeat any amendments,” the aide said.

McConnell was more blunt, warning that the agreement on the table is the only train leaving this year. “This agreement is not subject to being reopened,” he said.

“I hope that our friends in the House will understand that that’s the best way to go forward — simply pass the Senate bill, get it down to a president who supports the understanding,” he added.

Paul Singer contributed to this report.