California Republicans lost a fourth House seat Tuesday, as late vote-counting handed political newcomer Josh Harder enough votes to push GOP Rep. Jeff Denham from his seat in the agriculture-oriented Central Valley.

The loss, called by the Associated Press at 6:20 p.m. Tuesday, came as two other Republican-held seats to the South in Orange County were perilously close to flipping as the provisional and late mail-in ballots continued to break for Democrats.

Rep. Mimi Walters (R., Calif.) held an election night lead of more than 6,000 votes that has dwindled as the vote-counting has continued over the last week.

On Tuesday night, Walters's Democratic challenger Katie Porter, a UC Irvine professor who considers Sen. Elizabeth Warren (D., Mass.) a mentor, took the lead for the first time, edging Walters by just 261 votes.

Republican Young Kim, a former assemblywoman and a longtime aide to retiring Rep. Ed Royce (R., Calif.), also saw her lead fall, from 1,957 to just 839 votes against Gil Cisneros, a former Navy veteran and lottery winner after a major vote dump by Los Angeles County, the most liberal of the three counties portions of which make up her district.

The Kim and Cisneros campaigns have traded barbs and accusations of vote-counting misconduct over the past few days and each have pledged to keep a close watch on the process.

"We continue to observe the ballot counting process and remain committed to upholding the integrity of this election," a campaign spokesman told the Washington Free Beacon late Tuesday. "The Young Kim campaign will work to assure that every legal ballot cast is counted."

Cisneros on Monday said his team is "very proud of the democratic momentum that everyone helped build in the 39th, and we'll continue to work to ensure every ballot is counted & every voice is heard."

The three seats are among the seven that Democrats heavily targeted after a majority of voters in those districts voted for Hillary Clinton in the 2016 presidential election.

On election night, it appeared that Democrats had managed to flip just three of the seven seats, knocking off GOP Reps. Dana Rohrabacher and Steve Knight, while Mike Levin handily defeated GOP candidate Diane Harkey in the race to replace retiring GOP Rep. Darrell Issa.

Now, after nearly a week of vote counting, Democrats have picked up four with two more GOP seats in serious jeopardy of falling to the Democrats.

Only Rep. David Valadao (R., Calif.), also in the Central Valley, appears to have strengthened his position in late vote-counting: Valadao on Tuesday evening added another 153 votes to his margin, which has crept up to 2,444 votes in the past week against Democratic opponent T.J. Cox

If Republicans lose all six seats, they will have no representation in Orange County, once a conservative bastion that President Reagan famously described as the place "good conservatives go to die," for the first time in modern political history. They also will hold just eight of the state's 53 seats and none of the U.S. Senate seats.

The poor GOP showing has prompted prominent Republicans in the state to argue that the party needs to do some soul-searching. There are still nearly an estimated 4.5 million registered Republicans in the state, but they make up just 25 percent of the electorate with 44 percent, or 8.4 million registered Democrats in the state.

Even though California's voter registration hit an all-time high ahead of the November election, both Republicans and Democrats saw their ranks shrink between May, before the primary, and September, while the number of unaffiliated registered voters continued to climb to 27 percent.

Prominent Republicans called for a party-wide reckoning. Travis Allen, a Republican member of the California State Assembly representing Huntington Beach who ran an unsuccessful campaign for governor this year, called for new leadership of the Republican Party in California.

"The days of the Republican Party losing ARE OVER," he wrote in a Tweet. "It's time for NEW LEADERSHIP in California. It's time we ORGANIZE TRUE REPUBLICANS across our state to FIGHT and WIN. It's time to TAKE BACK CALIFORNIA." [Emphasis in original.]

Another veteran GOP legislator blamed the party for failing to differentiate itself from President Trump and the national Republican Party.

Kristin Olsen, a former state Assembly GOP leader, wrote in a piece on CalMatters website that the "California Republican Party isn't salvageable at this time."

"The Grand Old Party is dead—partly because it has failed to separate itself from today's toxic, national brand of Republican politics," she wrote.

"I and others have been warning people for years that this day of reckoning was coming if we didn't do something different," she added. "And as Election Night proved, the day has come."