LOS ANGELES (AP) — Democrat T.J. Cox claimed victory Wednesday over Republican U.S. Rep. David Valadao after an updated vote count increased his lead in a California farm-belt district.

Cox, who trailed in the vote tally until Monday, increased his lead to 506 votes after updated numbers were released by Kings and Tulare counties.

Votes still are being counted in the district's other two counties — Fresno and Kern — but balloting from those areas have favored Cox in post-Election Day updates, prompting him to declare the race over.

"I am elated to announce that we have won the election for California's 21st Congressional District," he said in a statement.

He thanked his wife and family and a campaign staff that never gave up "even when the outlook may have seemed dim."

Valadao did not immediately respond to Cox's announcement.

If Cox's lead holds, Democrats will have picked up seven GOP-held seats in California and will begin the new session with a 46-7 advantage in the state's congressional delegation.

Valadao easily carried the district in 2016, even though Democrats have a 16-point edge in voter registration. The dairy farmer and former state legislator had maintained his popularity by focusing on water issues critical to agriculture and had backed proposals to settle the legal status of people brought to the country illegally as children, a tip to the district's heavy Hispanic population.

But he was vulnerable in an election year where he continued to support President Donald Trump while Californians exhibited intensifying opposition to the White House. That dynamic played out in Orange County, where the last four Republican seats in what was once a GOP stronghold went to the Democrats.

Democrats also picked up the last Republican-held House seat anchored in Los Angeles County, when Democrat Katie Hill ousted Republican Rep. Steve Knight, and the Central Valley seat held by Republican Rep. Jeff Denham, who was defeated by Democrat Josh Harder.

Cox, an engineer who founded two nut-processing businesses, lashed Valadao in ads as a foot soldier for the Trump agenda who enjoyed government health benefits while voting to upend the Affordable Care Act.

While the election delivered mixed results around the U.S., it affirmed California's reputation as a Democratic fortress.

Democrats held every statewide office — again. The party holds a supermajority in both chambers of the state Legislature, and a 3.7-million advantage in voter registration. There wasn't even a Republican on the ballot for U.S. Senate for the second consecutive election.