President-elect Donald Trump is set to take office in January with a razor-thin GOP majority in the House of Representatives that offers Republicans barely any margin of error.

Overnight Wednesday, one of two outstanding races in California tipped toward Democrats, giving Adam Gray a roughly 182-vote lead over GOP Rep. John Duarte in the inland 13th Congressional District in the San Joaquin Valley. In California's 45th Congressional District, anchored in Orange and Los Angeles Counties, Democrat Derek Tran has a roughly 600-vote lead over Republican Rep. Michelle Steel.

In Iowa, GOP Rep. Mariannette Miller-Meeks is up by 800 votes in Iowa’s 2nd Congressional District, though a recount is unlikely to change the result in the competitive district. Miller-Meeks first won her seat in 2020 by six votes.

If these results hold, the House will start with a 220-215 GOP majority, even thinner than the current Congress' margin.

Republican ranks, however, drop to 219 with former Rep. Matt Gaetz's resignation. It could fall further to 217 depending on the timing of the resignations of Reps. Elise Stefanik, R-N.Y., and Mike Waltz, R-Fla., who are set to join the Trump administration as U.S. ambassador to United Nations and national security adviser, respectively.

That would send the chamber to a 217-215 margin -- giving Republicans no room for error, since any tied votes at 216-216 would fail.

Speaker Mike Johnson, R-La., has pleaded with Trump to avoid taking any more House members for his administration.

"It's a great problem to have," Johnson said on Fox News earlier this month. "We have an embarrassment of riches in the House Republican Congress. Lots of talented people who are very attuned to the America First agenda, and they can serve the country well in other capacities."

"But I've told President Trump, enough already, give me some relief. I have to maintain this majority. And he understands that, of course, we've been talking about it almost hourly every day," he added.

Already, Republicans have dealt with chaos in the current Congress.

Bands of hardline members have grown just large enough to block votes on bills, moves that were once viewed as beyond the pale within the halls of Congress. And, unforgettably, Republican divisions left the House without a speaker for days, both at the beginning when Kevin McCarthy was looking to get the requisite support and again after he gave up the gavel and members were torn for days before coalescing behind Johnson.

Heading into the current Congress, Republicans have sought to grease the skids a little bit more to try to avoid such public brawls from happening in the future.

Republicans agreed to raise the number of lawmakers needed to trigger a vote to oust a speaker from one to nine. In return, lawmakers who oppose proposals to allow votes on bills will not face retaliation.

But with such a narrow margin, any one Republican could and throw the floor into chaos and block the party-line passage of key bills.

One of the largest legislative items up for business is an extension of the 2017 tax cuts that Trump pushed during his first term. They're set to expire next year, and Republicans have hoped to extend them -- but 12 House Republicans voted against the 2017 GOP tax law, which only passed thanks to a larger majority at the time.

In 2017, when Republicans passed a rewrite of the tax code during the first Trump administration, 12 House Republicans -- part of a larger majority at the time -- voted against the bill, but did not prevent its passage.

Republicans began the 118th Congress in 2023 with 222 seats -- a 10-seat margin over 212 Democrats -- a majority that spent weeks in the winter selecting a House speaker, and a chunk of the fall selecting a replacement.

A few illnesses, special election surprises, or absences could also disrupt Republicans' careful balancing act.

In 1917, Republicans held the narrowest majority in history with a 215-213 edge over Democrats. But a group of minor party lawmakers worked with the minority to elect a speaker, delivering the chamber to Democrats, according to Pew.