Democrats succeeded Tuesday in winning back a majority in the House of Representatives, and they appeared Wednesday to claim at least three closely watched Southern California congressional races, but a tally of lingering ballots could still change the outcome in the neck-and-neck contests.

In one of the most closely-watched races in the state, Democrat Harley Rouda, a real estate investor, held a razor-thin lead over Republican Rep. Dana Rohrabacher in the coastal 48th District in Orange County.

Rohrabacher once represented a slim coastal strip of Long Beach in what was considered one of the most gerrymandered districts in the country. The district is now firmly planted in Orange County, extending from Seal Beach to Huntington Beach and part of Santa Ana and other cities.

Rouda, who portrays himself as a political moderate, is a former Republican who says he wants to protect health-care coverage and Social Security and Medicare.

Rohrabacher, who has been criticized by Democrats for his close relations with Russia, opposed the Trump tax-cut package but backs the president’s vocal stances on immigration.

Rouda has raised significantly more money in the race, saying he needs to spend heavily to have a chance at unseating a 15-term incumbent.

The tight nature of the race—about 2,600 votes separated the candidates with all precincts reporting— means the result likely won’t be known for weeks as provisional and mail ballots continue to be processed.

The bulk of the seats targeted by Democrats in Tuesday’s election are in the once-reliable Republican stronghold of Orange County, which has seen a liberal political shift over the years.

Two years ago, Democrat Hillary Clinton beat President Donald Trump in Orange County, the first time a Democrat won the county since Franklin Delano Roosevelt. That has encouraged Democrats, and for the first time the national organization has sent professionals to Orange County to help elect more Democrats to Congress.

In the 39th District in northern Orange County, Republican Rep. Ed Royce is stepping aside, and fellow Republican Young Kim appeared to win the race to replace him Tuesday. With all precincts reporting, Kim had 51.3 percent of the vote, holding a roughly 3,900-vote lead over Democrat Gil Cisneros. It was unknown how many provisional, late or mail-in ballots still remain to be counted in the district.

Cisneros, a noted philanthropist, won a $266 million Lottery jackpot in 2010 and injected $9 million of his own money into the race. Kim, a South Korean immigrant, worked for Royce for about 20 years before winning a seat in the state Assembly, where she served a single term. She is looking to become the first Korean American woman to win a congressional seat.

In the 49th District, which straddles Orange and San Diego counties and includes cities such as San Clemente and Oceanside, Republican Rep. Darrell Issa is stepping aside after an unexpectedly narrow reelection win two years ago.

Mike Levin, a Democratic environmental lawyer, held roughly 5-percentage-point lead over Republican state Board of Equalization member Diane Harkey Wednesday morning in the race to replace Issa. Ballots were still being tallied in the San Diego portion of the district.

Levin has never held political office, but he has served as the executive director of the Democratic Party of Orange County. Prior to sitting on the Board of Equalization, Harkey served in the state Assembly from 2008 to 2014, representing southern Orange County. She also served on the Dana Point City Council. Harkey received Trump’s endorsement in August and is a major backer of the campaign to repeal the state gas tax.

Republican Rep. Mimi Walters was targeted by Democrats in the 45th District, which covers a wide swath of Orange County, including Irvine, Lake Forest and Mission Viejo. But she appeared to be on pace to fight off a challenge from Democrat Katie Porter, a UC Irvine law professor who was critical of the Republican tax cuts and touted her role as a consumer advocate.

Semi-official results show Walters victorious with 51.7 percent of the vote, with an unknown number of ballots still left to count.

Walters has represented the district since 2014, and while it has become more Democratic, she easily won re-election in 2016—even as the district’s voters supported Clinton over Trump. She has continued to preach tax cuts, backing the Republican-engineered tax cuts.