SOLANA BEACH, California (NYTIMES) - Candidates from governor and senator to county assessor and city councillor used the final hours before Tuesday's (June 5) primary to campaign across California, but state and national Democrats were anxiously watching three Orange County House districts where they fear their glut of contenders could lock them out of the general election.

After pouring millions into television commercials, digital advertising and mailers in side-by-side districts held by Representatives Dana Rohrabacher, Darrell Issa and Ed Royce who are all Republicans, Democrats remained uncertain that one of their own would emerge as one of the two leaders in each of the contests.

Under California's so-called top-two system, only the two top vote-getters, regardless of party, make it to the November ballot.

With seven Republican-held seats that Hillary Clinton carried in 2016, California is a linchpin to Democratic hopes for taking back control of the House.

But the liberal backlash to President Donald Trump here has prompted so many to pursue office that Democrats fear their candidates will divide the vote and leave the party that has won every statewide election for a decade without a general election candidate, in what should be winnable races.

"I try not to worry about what I can't control," said Gil Cisneros, the Navy veteran and lottery jackpot winner whom national Democrats have rallied behind in the campaign to replace Royce, who is retiring.

Standing in his Brea, California, campaign office before heading out for an eleventh hour round of door-knocking, his 4-year-old twins running between his legs, Cisneros added: "We knew with so many people in the race we would need to focus on getting our name out there, our message out there early on."

The race to succeed Governor Jerry Brown and the question of whether veteran moderate Senator Dianne Feinstein would be vulnerable to a challenge from the left were once thought to be the most high-profile 2018 California races.

But Lt. Gov. Gavin Newsom has emerged as the clear favourite in the governor's race, with a Trump-endorsed Republican, John Cox, seemingly well positioned to finish second on Tuesday.

Antonio Villaraigosa, a former Los Angeles mayor, was far outraised by Newsom, and the likely Republican nominee got a lift when Representative Kevin McCarthy, the House majority leader, encouraged Trump to tweet his support for Cox.

And in the Senate race, Feinstein has overwhelmed her leading Democratic opponent, Kevin de León, the state Senate president, with money - some of which she gave herself.

For much of this spring, Democrats were most uneasy about not getting a candidate through in Rohrabacher's seat and one farther south along the Pacific that is currently represented by Issa, who is retiring. But in the last week, they have grown more alarmed by early voting trends in the seat held by Royce that show a more Republican-leaning electorate.

Assemblywoman Young Kim, a Republican, is virtually certain to emerge as the leading vote-getter overall in the district, but Democrats are concerned that Cisernos' vote may be diluted by three others in his own party - hopefuls like Mai Khanh Tran, a first-time candidate.

Braving the blistering Southern California sun Monday morning, Patti Adams and her daughter, Olivia, set out to erect signs for Tran, a Vietnamese refugee and physician.

Adams, a 53-year-old educator, typifies the newly engaged Californian Democrats: She watched elections from the sidelines all her life, she said. Then Trump's presidential victory and his policies on health care, education, immigration and the environment compelled her to change from an informed voter to a campaign activist.

"It has been so empowering for me," she said, as she drove around with a stash of signs in her silver Dodge Caravan. "It's better than typing my thoughts on Facebook."

A similar dynamic is playing out in Rohrabacher's district, which hugs the Pacific from Seal Beach south to Laguna Beach, where 15 candidates are seeking his job.

National Democrats have rallied behind Harley Rouda, a wealthy business executive. But they have been battling a remaining handful of Democrats still in the race and confronting an even thornier challenge: five Democrats who are not in the race but whose names are still on the ballot.

Alarmed about these "ghost candidates," the House Democratic campaign arm printed pamphlets indicating who had dropped out of the race. But some internal polling still showed at least one of the former candidates still drawing votes.

The other challenge for Democrats in the district is the vulnerability of the incumbent: The Russia-friendly Rohrabacher has turned off some Republicans and cleared a path for Scott Baugh, a former assemblyman, to mount a formidable campaign.

Democrats have responded by unleashing a barrage of ads aimed at driving down Baugh's vote share and propping up a little-known, third Republican in the race, but it is unclear if that will be enough to get Rouda into the top two.

Democrats were, however, feeling more optimistic about their prospects in Issa's district, where a negative campaign against one of the Republican contenders, Assemblyman Rocky Chavez, appeared to have been effective.

Less clear, though, is which Democrat out of 16 candidates would emerge against the likely Republican standard-bearer, former Assemblywoman Diane Harkey, in a district that stretches from Camp Pendleton south to La Jolla.

Polling is difficult among so many contenders, especially when few are very well known, but the three leading Democratic candidates appeared to be Sara Jacobs, the only woman in the Democratic field; Doug Applegate, a retired Marine colonel; and Mike Levin, a lawyer.

Jacobs, 29, was encouraged to enter the race by Emily's List, a fundraising organization devoted to electing women who support abortion rights. She said she sees her age and gender as strengths, though she said both have made it easier for people to question her qualifications.

"Voters really are looking for a change, for something different," Jacobs said. "And I provide the best, clearest example of what different looks like."

While the three Southern California districts could offer Democrats some unwanted drama on Tuesday, party officials felt broadly optimistic about their prospects in a state where undeclared voters now outnumber Republicans.

And perhaps nowhere are they more confident than in Representative Steve Knight's seat, one of the few Republican-held districts in Los Angeles County.

Younger, more left-leaning families who were priced out of the housing market closer to the city of Los Angeles have moved into the district, diversifying the population, which is now nearly 40 per cent Latino.

"This is the Democratic stronghold," said Bryan Caforio, one of the leading Democratic candidates in the race. "There are more Democrats in the Antelope Valley than anywhere else."

Not everyone agrees that the Democrats are in such a strong position. Patricia Garcia, 49, a registered Republican from Simi Valley, said she was not happy with how blue California had become. "It's becoming a little bit too liberal for us," she said. "We see California moving too far to the left."

Well to the north, in the state's Central Valley, Representative Jeff Denham is another Republican facing a threat in a district carried by Hillary Clinton.

And Jerry Kinkey, 71, is precisely the type of voter that Democrats are counting on this year.

In the driveway of his home in Tracy, Kinkey, a registered Republican and a Vietnam veteran, said he had flipped in this election. He voted by mail last week.

He dropped his support of Denham because of the lawmaker's vote to repeal the Affordable Care Act.

The top Democratic contenders to unseat him include Josh Harder, a former technology venture capitalist; Virginia Madueño, the former mayor of the small city of Riverbank; and Sue Zwahlen, an emergency room nurse.

So which Democrat did Kinkey pick?

There were so many names on the ballot, he can't remember. "I had to wing it," he said.