Congressional Republicans have split into competing factions over how to respond to President Obama’s expected moves to change the nation’s immigration system, which are likely to include protecting millions from being deported.

The first, favored by the GOP leadership, would have Republicans denounce what House Speaker John A. Boehner (R-Ohio) has called “executive amnesty” and use the party’s new grip on Congress to fight changes to the law incrementally in the months ahead.

The second, which has become the rallying cry for conservatives, would seek to block the president’s decision by shutting down the government for an extended period until he relents.

The brewing internal debate, which started to play out Thursday in meetings on both sides of the Capitol, represents the first significant test for Boehner and Senate Minority Leader Mitch McConnell (R-Ky.) since Republicans won full control of Congress, forcing them to balance their desire to show that GOP can govern and their fears of upsetting the conservatives who lifted them to power.

“It’s a big test for the leadership. We cannot listen to the loudest, shrillest voices in our party,” said Rep. Charlie Dent, a moderate Republican who represents the Philadelphia suburbs. “At some point we have to fund the government, and we should not fight to attach some demand. I don’t want to stand by and watch as our party gets driven into a ditch.”

Obama has pledged to use his executive powers to alter the immigration system before the end of the year, though it remains unclear exactly when he will act. He has asked top aides and Cabinet secretaries to present him with options but has not formally huddled with them to make a final decision, according to administration officials.

Among the options under consideration are proposals that could potentially protect as many as 6 million undocumented immigrants from deportation, according to several people familiar with Obama’s plans.

To better clarify his administration’s deportation policy, Obama is said to be considering instructions that would make clear that immigration agencies should focus on deporting criminals and repeat immigration offenders. New steps to stiffen security operations along the U.S.-Mexico border are also expected.

In a concession to the business community that Republicans would be hard-pressed to oppose, Obama is likely to expand visa programs for immigrants working for high-tech firms. Doing so would fulfill the wishes of Silicon Valley executives, the U.S. Chamber of Commerce and many GOP lawmakers who have advocated making it easier for high-tech firms to recruit skilled workers from overseas.

Obama’s allies on Capitol Hill have been closing ranks in recent days, preparing to help defend whatever decision the president makes.

Rep. Sheila Jackson Lee (D-Tex.) suggested that she and her colleagues would serve as a protective “ring” around the president once he takes action. “We’ll stay on fire, Mr. President,” Lee said, referencing a comment by Boehner that Obama was “playing with fire.”

Other Democrats reminded reporters Thursday that several of Obama’s predecessors have acted without congressional support.

“Abraham Lincoln signed the Emancipation Proclamation, and there was much to be said about it at the time. But he led with executive action,” said Rep. Al Green (D-Tex.), adding later: “When Truman signed the order desegregating the military, there was much being said. But it desegregated the military.”

Rep. Mario Diaz-Balart (R-Fla.), an advocate for an overhaul of immigration law, has been counseling House Republicans this week about the need to show empathy for undocumented workers as the party rails against the Obama administration, according to GOP aides familiar with his deliberations. He is concerned that too much vitriol could send the wrong message to Hispanic voters.

Still, Diaz-Balart said in a recent interview that Obama lacks the legal authority to act on his own and if he does so will upend any hope of bipartisan accord on a host of unrelated issues, including major trade agreements and tax reform.

“If the president ignores the fact that there’s going to be a new Congress in January, that makes it frankly almost impossible to get anything done,” he said.

Added Sen. John McCain (R-Ariz.), “This whole threat of an executive order has a chilling effect on everything.”

House and Senate negotiators have been working for weeks on legislation to fund the government past Dec. 11, when the current short-term spending deal expires.

The comprehensive agreement is expected to run through the end of the fiscal year in September. Aides in both chambers hope to bring the measure up for a vote before the Dec. 11 deadline.

A group of influential centrist Republicans told Boehner and his leadership team at a conference meeting Thursday that they must avoid another fiscal impasse and that this is the moment to take on the more extreme elements in their party. They argued that unless Boehner takes on Sen. Ted Cruz (R-Tex.) and other conservatives pushing for a hard-line response, he risks seeing his conference unravel into factions, much as it did last year during the 16-day shutdown that was cheered by the tea party.

Rep. Tom Cole (R-Okla.), a top Boehner ally, signaled Thursday that House leaders are working to avoid a shutdown and telling colleagues that opposing the president’s policy does not necessitate a standoff over government funding.

“Government shutdowns aren’t a way to solve problems,” Cole said in an interview. “It would only inflame the situation. What I say is: ‘Did it stop Obamacare? No, it did not.’ That’s unfortunate, but it’s not the weapon we should use.”

But Boehner, wary of upsetting his right-leaning conference, is taking care to criticize the president and show his members that even if he ends up departing from some of them on tactics, he shares their outrage about the president’s move. He also warned Thursday morning at the closed-door GOP meeting that Obama could cripple his ability to work with Congress for the remainder of his time in office.

“We’re going to fight the president tooth and nail if he continues down this path,” Boehner told reporters Thursday. “This is the wrong way to govern. This is exactly what the American people said on Election Day they didn’t want.”

While conservatives would like to use the budget debate as the battleground to fight Obama, Boehner said privately Thursday that he was also looking at judicial options, including expanding a proposed lawsuit over the president’s executive orders, which was introduced in the summer, to include immigration. A separate lawsuit on immigration and executive authority is another option.

Mark Krikorian, executive director of the Center for Immigration Studies, a nonprofit outfit that has opposed a comprehensive immigration overhaul, said he has been meeting with other influential “anti-amnesty” groups such as NumbersUSA and Eagle Forum. All are “gearing up” to persuade conservatives to use short-term spending bills as a means of dissent, he said.

“This is a race against time,” Krikorian said. “A long-term [continuing resolution] until the end of the fiscal year gives him the time he needs to implement the policy. If you pass a long-term bill, you’re giving up your best shot of winning concessions.”

Sen. Jeff Sessions (R-Ala.), the soon-to-be chairman of the Senate Budget Committee, is the leading voice in the chamber in favor of turning the budget negotiations into a clash over immigration. He said late Thursday that his way is the lone approach that could yield anything for the GOP, shrugging aside other ideas as mostly pointless potshots.

In an e-mail exchange, Sessions said passing a bill to fund the government beyond a few days, should a new immigration policy be implemented, “would be to acquiesce to the president’s unlawful action.”

McConnell, who will lead the upper chamber starting next year, has made clear that he is not willing to hold up government funding to settle scores with the president on immigration. “We’ll not be shutting the government down or threatening to default on the national debt,” McConnell twice told reporters Thursday.

Asked later what Senate Republicans might do to respond to Obama’s actions, McConnell demurred: “We’ll let you know.”

David Nakamura in Naypyidaw, Burma, and Sean Sullivan and Katie Zezima in Washington contributed to this report