(AP) — A handful of U.S. House contests in California appeared headed for close finishes as Republicans sought to gain ground after losing a string of seats to Democrats in a 2018 rout.

In a sign of the uphill fight for Republicans, President Donald Trump lost the heavily Democratic state to Joe Biden in a landslide Tuesday. The fate of GOP candidates in closely fought districts could hinge on whether voter disdain for Trump also creates a drag on candidates further down the ballot.

In the 50th District anchored in San Diego County, Republican former Rep. Darrell Issa, a prominent Trump supporter, trailed early but by Wednesday had built a nearly 13,000-vote lead in his race. In the 25th District north of Los Angeles, Republican Rep. Mike Garcia, another vocal Trump booster, was trailing Democrat Christy Smith by about 2,700 votes.

A large number of ballots went uncounted Tuesday in a year of widespread mail-in voting because of the coronavirus pandemic, which could leave the outcome of close races in doubt for days or weeks.

Two years ago, Democrats pulled off a series of upsets as suburban voters nationally recoiled from the Trump agenda, grabbing seven GOP-held districts, including four all or partly in the one-time Republican stronghold of Orange County.

Those losses were humiliations for the state GOP, which has seen its standing with voters steadily erode over a generation. Republicans hold only seven of the state’s 53 House seats, the party hasn’t won a statewide race since 2006 and registered Democrats outnumber GOP voters by nearly 2 to 1.

The party this year sought to claw back at least some of those seats, believing its candidates would be lifted by issues from resentment toward Sacramento’s long-running coronavirus orders to frustration with high taxes.

Republicans have high hopes for a comeback in Orange County, which was once considered a national GOP stronghold.

In the coastal 48th District, Republican Michelle Steel chased down first-term Democratic Rep. Harley Rouda, after he opened an early lead. Incomplete results had Steel with a small edge.

Rouda seized the seat in 2018 in an upset over then-Republican Rep. Dana Rohrabacher, who had served for decades. The loss carried symbolic weight in a county known as a foundation block in the Reagan revolution.

Steel, well known as the head of the county Board of Supervisors, benefits from a GOP registration edge in the district. Taxes and health care have been prominent issues.

Another close race was underway in the neighboring 39th District.

Democrat Gil Cisneros captured the demographically diverse district in 2018, and jumped out to an early edge Tuesday in his rematch with Republican Young Kim, a former state lawmaker. But she closed the margin and opened a tissue-thin lead.

Cisneros, a Navy veteran and $266 million lottery jackpot winner who founded a charitable foundation with his wife, has depicted Kim as a lockstep supporter of Trump, while she has argued that Cisneros didn’t live up to his promise to be an independent voice in Washington, instead falling in line with Pelosi.

In the 25th District, Democratic state lawmaker Smith was holding a narrow lead over Garcia, a former fighter pilot and defense industry executive.

The contest was a rematch from May, when Garcia won a special election after the seat was left vacant by the resignation of former Democratic Rep. Katie Hill, who stepped down amid a House ethics probe involving allegations of sexual misconduct.

Democrats had attacked Garcia as a Trump loyalist out of step with the district, which cuts through suburbs and small ranches in northern Los Angeles County and a slice of Ventura County that is home to the Ronald Reagan Presidential Library. Garcia has railed against high taxes, heavy regulation and Sacramento’s liberal mindset.

Issa was the favorite in the conservative-leaning 50th District, which Trump carried by 15 points in 2016. He had been a national figure as chairman of the House Oversight and Government Reform Committee from 2011 to January 2015, emerging as a chief antagonist of President Barack Obama.

But the surprisingly close race suggested that he might have been hurt by his close ties to Trump in an election in which the president was trounced in the state, or that some voters were uncomfortable with his district-hopping.

Issa, a car alarm magnate who at one time was the wealthiest member of Congress, earlier represented the neighboring 49th District, but nearly lost the seat in 2016 before deciding not to run for reelection two years later.

The 50th District was held by Republican Rep. Duncan Hunter until he resigned earlier this year after pleading guilty to a corruption charge. The 31-year-old Campa-Najjar nearly ousted Hunter in 2018 despite the district’s conservative tilt.

Campa-Najjar closed in on Hunter in the final batch of votes to be counted in 2018, and he maintained Wednesday that could happen again and he could wind up flipping the district.

“We’re still looking at the returns with a measure of hope and urge every last vote be counted,” he said. “The fact that it took the former wealthiest member of Congress to try and buy this seat proves how formidable our people-powered campaign is.”

Another closer-than-expected contest was shaping up in the Republican-leaning rural 8th District along the Nevada border. GOP candidate Jay Obernolte was leading Democrat Christine Bubser by about 4 percentage points for the open seat.

In the Central Valley, Republican former Rep. David Valadao was leading Democratic Rep. TJ Cox, who unseated him two years ago by 862 votes.

The Central Valley district has a wide Democratic registration advantage but has shown a willingness to embrace Republican candidates before. Valadao endorsed Trump this time after withholding his support in 2016 — a risk in a district the president lost by 15 points. But he also stressed an independent streak and an ability to work across the political divide.