The race between Republican U.S. Rep. Young Kim and Democrat Joe Carr for a seat in the Orange County inland state remained undecided by a narrow margin Tuesday night as vote counting continued.

President Biden narrowly won California’s 40th Congressional District in 2020, but Republicans maintain an approximately 5 percentage point advantage in voter registration.

In past years, the Congressional Democratic Party’s campaign arm included the district on its list of seats that could change from red to blue. But this year, the 40th Congressional District is not on the Democratic list and was deemed “likely Republican” by the nonpartisan Cook Political Report.

Kim lives just outside the district, which includes some of Orange County’s most conservative cities, including Yorba Linda and Villa Park. It also includes parts of Corona in Riverside County and Chino Hills in San Bernardino County.

The South Korean-born Kim served as a state legislator and ran unsuccessfully for Congress in 2018, but was elected two years later.

Mr. Kim has focused his campaign on lowering taxes and increasing cost burdens for middle-class households, a message that resonates primarily with voters in suburban districts.

Mr. Kerr served as fire chief for the Orange County Fire Department for 34 years and served as president of the Orange County Professional Firefighters Association, a union representing 800 firefighters, for 17 years. He ran for state senate in 2022 and unsuccessfully ran for the Orange County Board of Supervisors in 2018.

Much of Carr’s message centers on his time as a firefighter. In a recent ad, Carr pledged to help push for federal legislation to provide medical care for firefighters.