Republican Mike Garcia is the winner in the special election for California's 25th congressional district, NBC News projects.
Earlier Tuesday, his opponent Democrat Christy Smith conceded to him.
Garcia's victory brings the district back into the Republican fold, after it went blue in the 2018 midterms.
The seat was previously held by former Rep. Katie Hill, who resigned less than a year into her freshman term amid an ethics probe into an alleged relationship with a congressional staffer. She admitted to having a relationship with a female campaign staffer but denied having a relationship with a male congressional staffer. It is against House rules to have a relationship with a subordinate congressional staff member.
Hill defeated two-term GOP Rep. Steve Knight in 2018. Her victory was among those that propelled Democrats to a House majority.
The seat has been vacant since Hill stepped down in the fall of 2019.
In a statement, Garcia said he's "ready to go to work" for the people in the 25th Congressional District. "For too long, the people of our district have not had representation, and it's time their voice is heard in Washington," he said.
Garcia would represent the district until November, when he and Smith will face off again in the general election.
In a statement Tuesday, Smith congratulated Garcia, saying "we believe that the current tally shows" he is "the likely victor." She added that she looks forward to "having a vigorous debate about the issues in the upcoming November 2020 election."
Garcia, a former pilot, is a political newcomer with no legislative experience. Smith has been serving as a California assemblywoman since 2018.
In the 2016 presidential election, President Donald Trump lost the district by seven points to Hillary Clinton, his Democratic opponent.
Trump on Twitter has been rooting for Garcia and encouraging Californians to vote for him in the race.
California is one of 34 states that allow voters to cast mail-in ballots without requiring an excuse.
Last week, the state rolled out an expansion of vote-by-mail to help voters avoid contracting and spreading the coronavirus, which has forced several states and territories to alter the way they carry out elections this year.
Gov. Gavin Newsom on Friday signed an executive order allowing all registered voters in California to receive a mail-in ballot for November's election.