House Republicans could begin the new year grappling with a one-seat majority, a perilously slim margin for the 119th Congress as President-elect Donald Trump guns for an active first 100 days.

Last-minute GOP losses and exits in favor of the new administration mean Republicans could begin that period with precious little room for dissent, and one congressional race could decide the difference between a likely one- or two-seat majority. 

JOHNSON BLASTS DEM ACCUSATIONS HE VOWED TO END OBAMACARE AS 'DISHONEST'

Mike Johnson

House Speaker Mike Johnson could be presiding over a one-seat majority next year. (FOX News)

In California’s 13th Congressional District, Rep. John Duarte, R-Calif., is fighting for his political life against Democrat Adam Gray. 

As of Monday afternoon, Gray leads Duarte by a few hundred votes – a margin of roughly 0.1%. California state law mandates that counties certify their election results by Dec. 5.

If Democrats flip the seat, the House would have 220 Republicans and 215 Democrats heading into the New Year.

However, three Republican lawmakers’ departures are expected to whittle that down further. Now-former Rep. Matt Gaetz, R-Fla., resigned from the 118th and 119th Congresses amid consideration to be Trump’s attorney general.

MIKE JOHNSON WINS REPUBLICAN SUPPORT TO BE HOUSE SPEAKER AGAIN AFTER TRUMP ENDORSEMENT

A photo of John Duarte

Rep. John Duarte is fighting for his political life in the last uncertain House race. (AP Photo/J. Scott Applewhite)

House GOP Conference Chairwoman Elise Stefanik, R-N.Y., was tapped to be U.S. ambassador to the United Nations, and Rep. Mike Waltz, R-Fla., was named national security adviser. 

All three lawmakers represent deep-red districts, so there is little concern their seats will fall into Democrats’ hands. 

However, with special elections to replace Gaetz and Waltz set for April 1, and Stefanik’s not yet scheduled, the GOP may spend nearly all of their first 100 days controlling Washington’s power centers with a one-seat majority in the House.

House GOP Whip Tom Emmer, R-Minn., brushed off concerns about the prospects of holding a one- or two-seat edge in a recent television interview on FOX Business.

REPUBLICANS PROJECTED TO KEEP CONTROL OF HOUSE AS TRUMP PREPARES TO IMPLEMENT AGENDA

Emmer speaks at Minnesota Trump rally

House Majority Whip Tom Emmer dismissed concerns over a slim majority. (Stephen Maturen/Getty Images)

"That’s essentially what we’ve had over the last year, for better parts of the last year," Emmer told "The Bottom Line." 

CLICK HERE TO GET THE FOX NEWS APP

"I’ve got to tell you, I don’t give a darn whether it’s 222, 225, 218. As long as we have a majority, we can deliver with Donald J. Trump for the American people"

Ultimately, there is little daylight between a one- or two-seat majority, but if the 118th Congress is any indication, the numbers set up House Speaker Mike Johnson, R-La., with a tricky political situation.

House Republicans’ slim margins over the last two years enabled different factions of the GOP to paralyze the chamber floor at times over disagreements on government funding and other critical legislative fights.

Get the latest updates from the 2024 campaign trail, exclusive interviews and more at our Fox News Digital election hub.