A string of marquee U.S. House contests in California appeared headed for close finishes as Republicans sought to reclaim seats the party surrendered 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. The fate of GOP candidates in toss-up districts in Orange County, the Central Valley and the Los Angeles area could turn on whether voter disdain for Trump trickles down the ballot.

In the 50th District anchored in San Diego County, Republican former Rep. Darrell Issa, a prominent Trump supporter, was in a tight fight in his attempt to return to Congress. In the 25th District north of Los Angeles, Republican Rep. Mike Garcia, another unabashed Trump booster, was trailing Democrat Christy Smith. But in the Central Valley, Republican Rep. Devin Nunes, one of Trump’s strongest allies in Congress, had an edge over Democrat Phil Arballo.

Meanwhile, House Speaker Nancy Pelosi was easily reelected, while GOP House leader Kevin McCarthy was leading his race.

A large number of ballots were expected to go uncounted Tuesday in a year of extensive 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.

Republican presidential candidates carried California in nine of 10 presidential elections from 1952 to 1988. But the state has become increasingly Democratic with its diversifying population.

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 key contests:

A BATTLEGROUND AT THE EDGE OF LOS ANGELES

Incomplete results showed Democratic state lawmaker Smith with a slim edge over Garcia in the swing 25th District.

The contest was a rematch, after Garcia captured the vacant seat in a May special election against Smith. The district, cutting through suburbs and small ranches in northern Los Angeles County and hitched to a slice of Ventura County that is home to the Ronald Reagan Presidential Library, has a Democratic registration edge.

Democrat Katie Hill captured the seat in a 2018 upset, seizing what was then the last Republican-held House seat anchored in Los Angeles County. She was gone in less than a year, leaving an open seat after resigning amid a House ethics probe involving sexual misconduct.

Garcia is a former fighter pilot and defense industry executive.

THE COMEBACK KID?

In a surprise, Issa is in a close battle with Democrat Ammar Campa-Najjar in his bid to return to Congress.

Issa became 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 his once-conservative district straddling San Diego and Orange counties gradually became more Democratic, like much of California, and he decided not to run for reelection two years ago after nearly losing the seat in 2016.

Now, he’s back as a candidate in the neighboring 50th District, anchored in San Diego County. The seat was held by Republican Rep. Duncan Hunter until he resigned earlier this year after pleading guilty to a corruption charge. Issa is a car alarm magnate who at one time was the wealthiest member of Congress. The 31-year-old Campa-Najjar nearly ousted Hunter in 2018 despite the district’s conservative tilt.

Issa is closely aligned with Trump and could suffer if the president does not deliver a strong showing in the district that the president carried by 15 points in 2016.

FIGHT IN FARM COUNTRY

Former U.S. Rep. David Valadao lost his seat two years ago to Democrat TJ Cox by 862 votes. In their rematch this year, incomplete results showed Valadao with a narrow edge.

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.

Cox has been campaigning on health care and immigration reform in a district with a large Latino population. Both candidates have seen unfavorable publicity tied to their business interests.

GOP AIMS TO RETAKE LONGTIME REPUBLICAN DISTRICT

Republican Michelle Steel chased down Democratic Rep. Harley Rouda, after he opened an early lead in the coastal 48th District in Orange County. 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 in what was once considered a conservative bastion. The loss carried symbolic weight in a county known as a foundation block in the Reagan revolution.

Steel heads the county Board of Supervisors.

The district has a GOP registration edge, but Democrats have been closing in. Hillary Clinton carried the county by nearly 9 points in 2016. Taxes and health care have been prominent issues.

A REMATCH IN ORANGE COUNTY

Another longtime Republican seat anchored in Orange County fell to Democrat Gil Cisneros in 2018.

Incomplete results showed Cisneros trailing by a tissue-thin margin in his rematch with Republican Young Kim, a former state lawmaker. She earlier had lagged behind him.

The district has grown more Democratic over two years, and the party has opened up a registration advantage.

Kim has argued that Cisneros didn’t live up to his promise to be an independent voice in Washington, instead falling in line with Pelosi.

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.

DEMOCRAT DELIVERS WIN IN CENTRAL VALLEY

The Central Valley’s 10th District has a Democratic tilt, but the agriculture-rich area also has a history of sending Republicans to Congress.

Not surprisingly, first-term Democratic Rep. Josh Harder has been touting a willingness to work across the party divide, along with highlighting his work to secure funds for water projects, a priority in the region.

He scored a decisive win over Republican Ted Howze, a veterinarian.

Howze lost the backing of national Republicans earlier this year over derogatory online posts about Muslims and Hillary Clinton that the candidate said he did not write. He’s depicting himself as an outsider running against the Democratic establishment and has echoed Trump’s criticism of efforts to defund police departments.

Harder, a venture capitalist, had a nearly $4 million cash advantage in mid-October.