WASHINGTON — The new Congress will begin Friday, ushering in a tiny House Republican majority to tackle enormous tasks in the first year of Donald Trump’s second term, from keeping the government open to averting a calamitous debt default to advancing the president-elect’s immigration and tax ambitions.

Republicans won a 220-215 seat majority in the 2024 elections, but they will start with 219 members as former Rep. Matt Gaetz, R-Fla., has already resigned and vowed not to reclaim his seat.

That means House Speaker Mike Johnson, R-La., can afford no more than one defection in order to get re-elected as speaker in a public vote on Friday. But holding on to his job is the easy part: What comes next will present the biggest test of the Louisiana Republican’s political career.

Johnson’s majority is poised to shrink even further in the coming weeks, with Trump announcing he’ll pluck two House Republicans to serve in his administration — Michael Waltz of Florida to be national security adviser and Elise Stefanik of New York to be United Nations ambassador. Replacing them is likely to take months.

If both leave before Gaetz is replaced, that would cut the majority to an even more tenuous 217-215, meaning a single Republican defection could tank a bill unless Democrats vote in favor.

In other words, House Republicans will have a zero-vote margin for defection in the crucial early months of Trump’s presidency. Even when the party returns to full strength, the House majority could have trouble passing party-line legislation if a handful of members fall ill, have scheduling conflicts or experience weather delays preventing them from getting to Washington in time for key votes. Republicans will have a slightly larger majority in the Senate, 53-47, when senators are sworn in Friday and begin work on scheduling hearings for Trump’s Cabinet nominees.

And they have a tall to-do list. Here’s what is on the 2025 agenda.

Funding the government by March 14

Last month’s drawn-out fight over a short-term bill to prevent a government shutdown just punted the deadline to March 14, less than two months after Trump takes the oath of office. That means Republicans still need to cut a deal with Democrats on how to fund the government, which routinely causes clashes between GOP moderates, military hawks and conservative hard-liners.

If history is any guide, House Republicans are unlikely to find enough votes to pass a bill without Democrats, as they always lose some votes on the right. But even if they manage to unify their House conference, they will need 60 Senate votes to make a law, which means House Minority Leader Hakeem Jeffries, D-N.Y., and incoming Senate Minority Leader Chuck Schumer, D-N.Y., will need to sign off on any deal in order to prevent a shutdown.

That means Johnson will ultimately have to sell another compromise package to members who routinely raise hackles against such bills.

Pass Trump’s agenda on immigration, energy and taxes

Republicans hope to move quickly on legislation to advance core components of Trump’s agenda. They’ve made clear they will use the budget “reconciliation” process to bypass the Senate’s 60-vote rule and pass a bill with only Republican votes.

That process has limitations. It begins with passing a budget resolution to lay down fiscal parameters and instruct committees, and then the final bill can only make changes to spending and tax policy, which will require compromises that conservatives would prefer not to accept. Democrats can challenge and strip out any provisions that are not tax- or spending-related and thus don’t qualify for the 50-vote path.

Disagreements have already spilled out into the open. Incoming Senate Majority Leader John Thune, R-S.D., is pushing for breaking it up into two bills in hopes of getting a quick victory on giving Trump more border security funding before bringing up another party-line measure later this year to extend Trump’s tax cuts ahead of their expiration on the last day of 2025. But the chair of the tax-writing Ways and Means Committee, Rep. Jason Smith, R-Mo., is warning Republicans that delaying the tax bill could jeopardize it and risk a multitrillion-dollar tax hike.

Whichever strategy they pursue, Republicans will also have to achieve near-unanimity on divisive questions like how much to add to the deficit and which parts of outgoing President Joe Biden’s legacy achievements to repeal in order to pay for their new policies. The latter is more complicated than it sounds — major portions of the Biden clean-energy programs that GOP leaders are targeting for repeal benefit conservative districts represented by Republicans.

Extend the debt ceiling

Under a bipartisan law signed last year, the U.S. is poised to hit the debt ceiling this month and will begin to use “extraordinary measures” to pay the bills and prevent a default that could have catastrophic consequences for the American — and global — economy. That’s likely to buy Congress a few months, but members will invariably have to extend the debt ceiling sometime this year.

Last month, Trump’s eleventh-hour demand that Congress take the debt ceiling off his plate was widely rebuffed by both parties. Despite Trump’s threat to court primary challenges against Republicans who voted for a funding bill without resolving the debt limit, 170 GOP members supported such a measure.

Many Republicans routinely vote against lifting or extending the debt ceiling. But Democrats, who usually fill the void, may be reluctant to help Republicans lift the debt ceiling just as the GOP is passing a party-line tax bill the opposition says would primarily benefit the wealthy.

So, will Republicans cut a deal with Democrats? Will they find a way to raise the borrowing limit with only GOP votes, perhaps in a reconciliation bill?

Behind closed doors last month, Republicans made a pact to pursue $2.5 trillion in spending cuts in 2025 alongside a debt limit hike, a way to appease conservative hard-liners. But some say that deal isn’t worth the paper it’s printed on.

“They call that a gentleman’s agreement,” Rep. Tim Burchett, R-Tenn., who has opposed past bills to lift the debt limit, told NBC News. “And there are no gentlemen up here, dude.”