With President Obama's long-awaited move to halt deportations for millions of undocumented immigrants looking more and more like a fait accompli, congressional Republicans are trying to figure out if they can stop him.

The White House has been promising the executive order for months over the protestations of GOP leaders, and The New York Times reported on Thursday that the action could come as soon as next week and affect up to 5 million immigrants. "We’re going to fight the president tooth and nail if he continues down that path," Speaker John Boehner told reporters late in the afternoon upon his reelection as the House's top Republican. "All options are on the table."

At a press conference in Burma early Friday morning, Obama reiterated his plan to take action before the end of the year. "That's going to happen," he said. Yet he said Republicans still had an opportunity to pass immigration legislation in the lame-duck Congress, something Boehner has no intention of doing.

If Obama acts this month, the biggest question will be whether the GOP tries to insert language into a must-pass federal spending bill to overturn the policy, thereby risking a government shutdown that party leaders have promised to avoid. The incoming Senate majority leader, Mitch McConnell, signaled he would not pursue that option. "We will not be shutting the government down or threatening to default on the national debt," he said repeatedly on Thursday in response to questions from reporters about the possible strategy.