WASHINGTON (AP) — The first -- and maybe only -- step toward filling the seat vacated by former House Speaker Kevin McCarthy kicks off Tuesday with a special primary in California’s 20th Congressional District.

McCarthy, whose brief tenure as speaker was marked by infighting and gridlock, announced his resignation in December, two months after hard-right members of his conference successfully engineered his ouster. He had represented the Central Valley-based seat — one of the state’s few reliably red districts — since 2007.

It will be the second election in as many weeks for the district. The primary for a full term starting in January 2025 was held on March 5. Tuesday’s primary is to complete the rest of McCarthy’s term.

There are nine candidates on the ballot. All candidates run on the same ballot, regardless of party. If the top candidate gets more than 50% of the vote, that candidate wins the seat through the end of the year. If no one tops 50%, the top two candidates advance to a May 21 runoff election.

There are four Republican candidates running, including the front-runners Vince Fong, a state assemblyman, and Mike Boudreaux, the Tulare County sheriff. Fong has received endorsements from McCarthy, whom he used to advise, and former President Donald Trump, while Boudreaux has more local support, including from countyleaders and several Republican groups in the district.

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Democrats have lined up behind Marisa Wood, who advanced to the general election against McCarthy in 2022 but finished third in the March 5 election.

Regardless of what happens in the special election, the district is guaranteed to be represented by a Republican in the next Congress, with Fong and Boudreaux advancing to the general election for a full term.

Republicans hold a narrow majority in the U.S. House, 219-213, with three vacancies, though a special election to fill a vacant seat in Ohio is also taking place Tuesday and another representative announced he will resign on March 22.

A look at what to expect on election night:

SPECIAL ELECTION DAY

The special primary election in California’s 20th Congressional District will be held Tuesday. Polls close at 11 p.m. EDT.

WHAT’S ON THE BALLOT

The Associated Press will provide coverage for one contest in California on Tuesday: the special primary in the 20th Congressional District. The Democratic candidates on the ballot are Wood and Harmesh Kumar. The Republican candidates are Fong, Boudreaux, Kyle Kirkland and Anna Cohen. The remaining three candidates are Ben Dewell, David Fluhart and James Cardoza, all running as “no party preference.”

WHO CAN VOTE

Any voter registered in California’s 20th Congressional District may participate in this special election.

DECISION NOTES

This district includes portions of Fresno, Kern, Kings and Tulare counties in the San Joaquin Valley, one of the basins in the state’s agricultural-heavy Central Valley. It’s a reliably Republican area, as the San Joaquin Valley-based seat has been held by a member of that party since 2003. Trump won this district by 25 percentage points in the 2020 general election against Democrat Joe Biden. That year, McCarthy won reelection over Democrat Kim Mangone by 24 percentage points. He improved on that margin in the most recent election: He won all four counties with at least 64% of the vote and beat Wood by 33 percentage points.

Like McCarthy, Fong is from Bakersfield, a city of more than 400,000 residents in Kern County. His state assembly district overlaps with the congressional district, as it includes parts of the city and the area northeast of it. His candidacy for McCarthy’s seat was initially rejected by state election officials because he had already filed to run for reelection in his assembly district and state law prohibits candidates from running for two offices in the same election. But a judge ruled in late December that Fong could run, since the state law did not apply to California’s top-two primary system.

Boudreaux is the thrice-elected sheriff in Tulare County, which is split up among three congressional districts. In the 20th District, Tulare is the smallest share of the congressional district. Boudreaux won his first election for sheriff-coroner in 2014 with almost 73% of the vote and ran unopposed in 2022 and 2018.

The special primary is likely to have much lower turnout than the March 5 primary, which took place on the same date as the state’s presidential primaries. In that election, Fong came in first with about 41% of the vote, and Boudreaux came in second with 25%. The two will face off in November for a full term, regardless of what happens in Tuesday’s primary.

The Associated Press does not make projections and will declare a winner only when it’s determined there is no scenario that would allow the trailing candidates to close the gap. If a race has not been called, the AP will continue to cover any newsworthy developments, such as candidate concessions or declarations of victory. In doing so, the AP will make clear that it has not declared a winner and explain why.

WHAT DO TURNOUT AND ADVANCE VOTE LOOK LIKE

As of Oct. 3, 2023, there were nearly 449,000 voters registered in the 20th District. Of those, approximately 121,000 are Democrats (27%) and 208,000 are Republicans (46%).

Ballots were mailed out on Feb. 19, and ballot drop boxes opened the following day.

HOW LONG DOES VOTE COUNTING USUALLY TAKE

It takes a long time. In the state primary election in March, the AP first reported results in the district at 11:11 ET, or about 11 minutes after polls closed. The election night tabulation ended at 5:10 a.m. ET with about 51% of total votes counted.