Letlow will be joining the House in the seat originally won by her husband, Luke Letlow, who died in September from COVID-19 before he was supposed to be sworn in. Julia Letlow won a special election in March.
This gives Republicans 212 seats in the House, catching up to Democrats' 218. Since tie votes fail in the House, that means Democrats cannot lose more than two votes from their party to pass legislation if the GOP fully opposes them.
That slim margin of error could prevent Democrats from passing more progressive bills that moderates in their party may not support.
Some reinforcements may soon be on the way, however, with Democrats favored in two of the three House special elections that will be held over the next two months.
A special runoff election in Louisiana’s 2nd Congressional District will be held on April 24 – and the two candidates facing off in the solidly blue district are both Democrats. The race is to fill the seat of former Rep. Cedric Richmond, who stepped down to join President Biden's administration as senior adviser and director of the Office of Public Liaison.
While May 1 will see a special election in Texas' Republican-leaning 6th Congressional District to fill the seat of GOP Rep. Ronald Wright, who died of COVID-19 complications, there will be another special election on June 1 in New Mexico's blue 1st Congressional District to fill the seat of former Democratic Rep. Debra Haaland, who was confirmed as interior secretary.
Another special election in a deep blue district -- Ohio's 11th -- won't be held until Nov. 2 to replace former Democratic Rep. Marcia Fudge, who was confirmed as Housing and Urban Development secretary.
In the meantime, Democratic leadership has remained confident in the face of shrinking leverage.
"Frankly, we're doing OK as Democrats as you look at this quarter," House Majority Leader Steny Hoyer, D-Md., said in March.
Similarly, House Speaker Nancy Pelosi said last March that advancing her party's agenda is "not going to be a problem."
Fox News' Chad Pergram, Paul Steinhauser and Kelly Phares contributed to this report.