California voters are set to choose a replacement for former Speaker Kevin McCarthy in a special election Tuesday that will help pad the House GOP’s slim majority.

The race in the Bakersfield-area 20th District between two Republicans, state Assemblyman Vince Fong and Tulare County Sheriff Mike Boudreaux, will determine who will serve the remainder of McCarty’s term. He resigned in December two months after he was ousted as speaker.

Unlike in most states, California utilizes a top-two primary system where all candidates appear on the same primary ballot regardless of party. While one candidate can win a special election outright in the primary if they win a majority of the vote, neither Fong nor Boudreaux hit that mark back in March.

Fong won the most votes in that primary and is seen as the favorite, backed by both McCarthy and former President Donald Trump. 

Washington Republicans will get a win no matter what, since filling the seat gives them a bit more flexibility in a narrowly divided Congress. Counting a GOP victory Tuesday, Republicans will have 218 members of Congress to the Democrats’ 213, with four vacancies. That gives House Speaker Mike Johnson a bit more cushion — in recent months, some conservative members of the party have threatened to sink key rules and pieces of legislation. 

Voters will also head to the polls on Tuesday in four other states for primary elections, setting up matchups in key battlegrounds and settling intraparty feuds. 

Trump’s endorsement is also on the line in an open House race in Georgia’s 3rd District, where his former White House political director is running. In the 2nd District, Chuck Hand, who pleaded guilty to a misdemeanor related to his conduct during the attack on the U.S. Capitol on Jan. 6, 2021, is among the GOP candidates looking to take on Democratic Rep. Sanford Bishop.

Elsewhere in Georgia, Fulton County District Attorney Fani Willis is facing her own primary as she oversees Trump’s election interference case in the state. And conservative state Supreme Court Justice Andrew Pinson is facing a challenge from former Democratic Rep. John Barrow, who has centered his campaign on abortion rights.

In Kentucky and Idaho, Republican members of Congress are looking to fend off primary challengers and overcome some outside attacks.  

Primaries in Oregon will set the matchups in three competitive districts, with national Democrats hoping to get their preferred candidate across the finish line in the 5th District. Democrats will also likely pick a new member of Congress in Oregon’s deep-blue 3rd District, where Washington Rep. Pramila Jayapal’s sister, former Multnomah County Commissioner Susheela Jayapal, is a top contender. 

Polls close in Kentucky at 6 and 7 p.m. ET, with the state split into two time zones; 7 p.m. ET in Georgia; 10 and 11 p.m. ET in Idaho; and 11 p.m. ET in California. Oregon conducts its elections entirely by mail, and ballots must be returned or postmarked by 11 p.m. ET Tuesday.