The U.S. Capitol looms in the background of a sign on the National Mall reminding visitors of the closures to all national parks due to the federal government shutdown, Oct. 3, 2013. Reuters

WASHINGTON – Congressional Republicans will have some hard choices to make about keeping the government open when they return to Washington in November. If Republicans take over the Senate, as appears likely, the pending battles over spending would be the first test of how the newly empowered GOP might operate.

Here's the problem: Funding for the government will expire on Dec. 11, and Congress must pass a spending bill to avoid a shutdown like the one that closed the government for 16 days last October.

There's a simple solution: Pass a bipartisan bill in December, called an "omnibus bill," which is being crafted in the House and the Senate. It will ensure the government stays open until October 2015. Leaders in both chambers appear to support this approach.

House Republican leaders have signaled that they aren’t interested in waging war over spending legislation or engaging in another shutdown battle. Getting the spending fights out of the way, leadership has argued, will position them in the public’s view as capable of governing.

“The issue is, often Republican leaders end up speaking only for themselves and not for the tea party caucus,” Rep. Chris Van Hollen, a Maryland Democrat and the ranking member of the House Budget Committee, said. (Van Hollen said he expects the Democrats to hold the Senate.)

This fall, rank and file GOP members have less incentive than ever to play nice. If Republicans pick up seats in the House and take control of the Senate, they'll be gunning for a fight with the White House. And warnings about political fallout from another shutdown are unlikely to scare them, since the last one appears to have inflicted virtually no harm on the party.

The omnibus bill would mean that there was no must-pass spending legislation that Republicans could use to create leverage on President Barack Obama. Attaching items that Obama opposes -- like changes to the health care law or energy and environmental policy -- to spending bills is a favored tactic among conservatives.

The Republicans could ditch the omnibus bill without causing a shutdown, in any case, by passing a short-term continuing resolution, also known as a CR, which would probably fund the government only until early next year.

That means the GOP could go back to the negotiating table with Obama in January -- when they might well hold both the Senate and House. That's an appealing prospect for conservatives eager to force Obama to accede to Republican demands like repealing pieces of the Affordable Care Act or allowing the construction of the Keystone XL pipeline.

But Democrats wouldn't want to pass a CR that pushes off key fiscal decisions to a time when they'll be the minority party and the president will be left alone to oppose Republican fiscal choices. It's not clear what Republicans could offer to get Democrats to vote for a continuing resolution.

Further complicating the matter is a couple of new spending requests that Obama is likely to make in the coming weeks -- more funding to address the Ebola outbreak in West Africa, perhaps more money to deal with the Islamic State group, formerly known as ISIS, and Syria. Energized by a midterm win, Republicans may tell the president he must find offsetting cuts, known as "pay-fors," in exchange.

And Congress has less than 15 working days to figure it out once they return to Washington after the midterms next week. Before leaving in September to campaign in their districts, members passed a short-term continuing resolution to keep the government open until Dec. 11 -- only a day before they anticipate departing for Christmas.

Political analysts and pundits will be watching how smoothly a Republican-controlled Congress can operate. And presumed 2016 presidential candidates like Sens. Rand Paul and Marco Rubio have an interest in making sure the party appears competent.

As messy as the next few months will be, soon Congress will have to start working on a budget and spending bills for next year.

The current omnibus measure being drafted is following the principles laid out in the Bipartisan Budget Act in 2013. That deal, brokered by Washington Sen. Patty Murray, a Democrat, and GOP Rep. Paul Ryan of Wisconsin, was part of a process established to end the shutdown in 2013. The deal expires this year -- meaning the next budget, for fiscal year 2016, will have to be crafted virtually from scratch.

Conservatives could be persuaded to pass the omnibus bill this year, with the promise that the following year’s budget will include the items Republicans have been clamoring for, like Medicare and Social Security overhauls.

"We'll have a whole other debate," Van Hollen said.