U.S. President Barack Obama speaks about immigration reform while at the Copernicus Community Center in Chicago on Nov. 25, 2014. Republicans are trying to find a way to reserve the president's executive order. REUTERS/Larry Downing

WASHINGTON – Congress returns to work Monday with a long to-do list: A funding bill must be passed by Dec. 11; a series of “tax extenders” are needed to prevent taxes from rising; lawmakers could pass an authorization-of-force bill that would provide more legal support for the fight against the Islamic State group; and then there is the fight over immigration.

President Barack Obama’s executive orders on immigration, which shield 5 million undocumented immigrants from deportation, will run out at the end of his presidency. So in theory, Republicans furious with what they call the president's "imperial" actions or his "amnesty" policy could simply wait him out and hope they win the White House in 2016. But by challenging the GOP to pass its own immigration bill if it doesn't like his policy, Obama has succeeded in putting Republicans on the defensive.

Republicans are about to be in the majority in both houses of Congress, so they should be able to pass a bill that's to their liking. But while the party is united in lambasting Obama, it's divided on any substantive immigration measures.

Since Obama announced his executive orders on immigration late last month, the GOP has offered plenty of political responses, including hinting that it won't offer the customary invitation for him to give his State of the Union address from the floor of Congress. Republicans could sue the president, which House Speaker John Boehner has already threatened to do, or try to censure him, as some conservatives, like Rep. Steve King, R-Iowa, have called for.

Could they actually pass an immigration bill? The Senate in fact passed an immigration bill, which hews quites closely to Obama's executive orders, with bipartisan support in June 2013, although right-wing opposition kept it from being voted on in the House.

But doing nothing has costs. The longer Republican lawmakers wait, the harder it will be to reverse Obama's policy: Offering people legal status and then taking it back would be logistically difficult and politically disastrous, perhaps even costing the GOP any chance at winning significant Latino support for a generation.

The Republicans' best option may be to force the president to accept some changes that would narrow his orders, using funding as leverage. The funding bill that must be passed by Dec. 11 is the first such opportunity.

The government pays for the process of issuing visas for those who apply, including those now covered by Obama's orders. Sen. Jeff Sessions, R-Ala., an opponent of the immigration policy changes, argues that lawmakers can just write a provision in the spending bill that orders the money not to be spent.

But Sessions' plan has some problems. For starters, Democrats still control the Senate, so they could strip out the provision when the bill is in their chamber, leading to a legislative show down. And Obama could refuse to sign it, which could lead to a government shutdown.

No one in Republican leadership, especially Sen. Mitch McConnell of Kentucky, who will soon be the majority leader, wants to see a shutdown.

Republicans are looking at a partial option: Fund the government until September 2015 – what Democrats want – except the parts of the government that execute immigration functions. Merging two words that are used to describe spending bills, the “CR” (for "continuing resolution") and “omnibus,” this option is being called a “cromnibus.” The immigration parts of the government would be funded only until early next year, when Republicans control the Senate and they can use the leverage of a partial shutdown to try to force Obama to reverse his order.

To fully use that leverage, those parts of the government might actually shut down. And the pieces that would be lost are the ones that Republicans like: enforcement and deportation operations.

“House Democrats have fought against Republican attempts to shut down the government,” Rep. Nancy Pelosi, D-Calif., the House minority leader, said. “We will not be enablers to a Republican government shutdown, partial or otherwise.”

Democrats might ultimately go along with the partial funding plan. It keeps most of the government funded for the year and allows them to portray the Republicans as unable to govern and as the cause, once again, of a shutdown.

The most unlikely scenario is that Republicans pass a bipartian, comprehensive bill. The Senate passed a comprehensive bill with a vote total of 68-32. More than 500 days later, the House has yet to take a vote on it.

That's not about to change. Even Republicans who quietly support the immigration policy changes aren’t going to support or reward -- as they see it -- Obama. And when Boehner has shown signs of cooperating before, the conservative members of his caucus rebelled, threatening to oust him. The so-called “Hastert rule” would keep the speaker from putting a bill on the floor if it didn't have GOP majority support.

Theoretically, the GOP could pass its own bill, something that moderate party leaders have been urging for months.

"It is time for Republican leaders in Congress to act,” former Florida Gov. Jeb Bush, a potential 2016 Republican candidate, said. “We must demonstrate to Americans we are the party that will tackle serious challenges and build broad-based consensus to achieve meaningful reforms for our citizens and our future."

The Senate-passed bill was carefully crafted to get bipartisan support. It includes a pathway to citizenship, which Republicans oppose, but not full amnesty, which Democrats wanted. It also includes a sizable increase in funding for border security, which was needed to gain Republican support but which drew criticism from Democrats.

It would be virtually impossible to craft another bill that would gain widespread bipartisan support without enraging the right wing. A Republican-written bill would probably be simply the GOP wish list and none of the provisions that Democrats want. The bill would likely be almost entirely focused on border control, and potentially include more deportations. And Obama would never sign it without provisions that legalize, in some way, the millions of people he gave shelter to last month.

Right now, Republicans seem more focused on trying to undo Obama’s executive actions than crafting legislation to fix an immigration system that they agree is broken. They can stall; they can create obstacles; and they can always shut the government down. Whether they can agree on a viable way forward remains to be seen.