LOS ANGELES (AP) — Republican candidates gained ground Thursday in updated vote tallies in closely contested California U.S. House districts, a promising sign for the party in its effort to retake seats lost to Democrats in 2018.

The contests were being closely watched in a state dominated by Democrats, where Joe Biden defeated President Donald Trump in a landslide. Republicans hold just seven of 53 House seats but have a chance to add up to four more.

In the 25th District north of Los Angeles, Republican Rep. Mike Garcia jumped ahead of Democrat Christy Smith by a slim margin in the latest count. Garcia won the vacant seat in a special election in May, marking the first time in over two decades that a Republican won a Democratic-held California congressional district.

In the 50th District anchored in San Diego County, former Rep. Darrell Issa extended his lead over 31-year-old Democratic businessman and former Obama administration official Ammar Campa-Najjar to more than 16,000 votes. The seat was vacated earlier this year by GOP Congressman Duncan Hunter after he pleaded guilty to a federal corruption charge.

In Orange County, Republican Michelle Steel added about 2,000 votes to her lead over Democratic Rep. Harley Rouda in the 48th District. And in the neighboring 39th District anchored in Orange County, Republican Young Kim padded her edge over Democratic Rep. Gil Cisneros, who beat her two years ago to win the seat

The Central Valley’s 21st District saw Republican former Rep. David Valadao add to his lead over Democratic Rep. TJ Cox. Valadao, who lost his seat to Cox in 2018 by less than 1,000 votes, now has a lead of about 4,000 votes.

The figures were unofficial, and tens of thousands of votes remained to be counted in the districts.

Should the Democratic-held districts fall to Republicans, it would add further dismay in the Democratic ranks in Congress, which saw their House majority shrink while some members heaped blame Thursday for the setbacks on Speaker Nancy Pelosi’s team. Before the election, Democrats expected to expand their advantage over Republicans.

The California figures were also a striking reversal from 2018, when Republicans in key districts came out of the election leading, only to see Democrats gradually overtake them with a count of late-arriving ballots.

In the 25th District, which straddles parts of Los Angeles and Ventura counties, the returns showed Smith with only a slight edge in Los Angeles County, where Democrats typically pile up large vote margins. The Ventura County slice leans Republican, where Garcia had an edge.

Kim’s advance was notable in a district that has a Democratic registration edge, though for years it was counted in the Republican ranks until the retirement of longtime Rep. Ed Royce.

Among the Democrats Rouda was perhaps most at risk heading into the election in a district with a 5-point Republican registration edge. Rouda seized the seat in 2018 in an upset over longtime Republican Rep. Dana Rohrabacher, a loss carried symbolic weight in a county known as a foundation block in the Reagan revolution.

Issa is hoping to make a return to Congress after deciding not to run for re-election in 2018 in the neighboring 49th District, now held by Democratic Rep. Mike Levin.

Campa-Najjar has emphasized his local roots, while Issa has campaigned on his experience, after serving 18 years in the House.

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Associated Press Writer Julie Watson in San Diego contributed.