President Donald Trump (L) shakes hands with Speaker of the House Rep. Paul Ryan (R-WI) (R) during a luncheon at the Congress of Tomorrow Republican Member Retreat last January.

Lawmakers hope to approve a must-pass spending bill on Thursday as the clock ticks toward potential government shutdown this weekend.

Despite the perilous situation, House Republican leaders are still struggling to unite the GOP rank-and-file behind a plan that would punt most of their remaining work into next year.

House GOP leaders unveiled a plan Wednesday evening at a closed-door meeting but a number of defense hawks opposed plans to put off a battle with Democrats until January.

There's still plenty of time to avert a politically debilitating shutdown of the government, and such a pratfall would detract from the party's success this week in muscling through its landmark tax bill. With Republicans controlling Washington, they would not have anyone else to blame for a shutdown debacle.

Some lawmakers from hurricane-hit states also worried that an $81 billion disaster aid bill was at risk of getting left behind in the rush to exit Washington for the holidays.

The upcoming short-term measure would fund the government through Jan. 19, giving lawmakers time next month to try to work out their leftover business.

Lawmakers said the GOP vote-counting team would assess support for the plan and that GOP leaders would set a course of action from there.

Rules Committee Chairman Pete Sessions, R-Texas, said "there's no specific direction right now" about the path forward. He spoke after an hour-long closed-door meeting of Republicans in the Capitol basement.

An earlier plan favored by pro-Pentagon members of the influential Armed Services Committee would have combined the stopgap funding bill, called a continuing resolution, with a $658 billion Pentagon funding measure. But the idea is a nonstarter with the Senate, especially powerful Minority Leader Chuck Schumer, D-N.Y.

Meanwhile, the $81 billion disaster aid bill faced a potential separate vote of its own, but was at risk of languishing because of opposition among some conservatives upset about its cost. Senate action on that bill, a priority of the Texas and Florida delegations, wouldn't come until next year anyway.

Democrats are opposing the GOP endgame agenda because their priorities on immigration and funding for domestic programs aren't being addressed. Opposition from Democrats means Republicans need to find unity among themselves, which once again is proving difficult. In such situations, congressional leaders often turn to lowest common denominator solutions, which in this case would mean a stopgap measure that's mostly free of other add-ons.

"The number of options is collapsing down," said Rep. Frank Lucas, R-Okla. "I have faith that at the last possible moment, to paraphrase Churchill, when we have no other choice, we'll do what we need to do."

Regardless of how the crisis of the moment will be solved, most of the many items on Capitol Hill's list of unfinished business are going to be pushed into next year.

Hopes for a bipartisan budget deal to sharply increase spending for both the Pentagon and domestic agencies appeared dead for the year and Democrats were rebuffed in their demands for protections for young immigrants brought to the U.S. illegally as children.

Sens. Lamar Alexander, R-Tenn., and Susan Collins, R-Maine, announced Wednesday that they would not seek to add the insurance subsidies, which are designed to stabilize the Affordable Care Act's markets. The tax bill repeals the requirement that individuals purchase insurance.

Trying to combine the health measure with the spending bill was a demand of Collins when President Donald Trump and Senate GOP leaders secured her vote for the party's tax cut measure. But House conservatives strongly opposed the move.

House Republicans weren't part of that deal, and with the tax vote over, it became plain that Senate leaders were not able to deliver for her.

Lawmakers said a short-term, $2.1 billion fix for an expiring program that pays for veterans to seek care outside the Department of Veterans Affairs system would be added to the package. So, too would a short-term "patch" to make sure the states facing shortfalls from the Children's Health Insurance Program, which pays for health care for 9 million children from low-income families, won't have to purge children from the program.