It was one of several nasty midterm shocks for California Republicans: Internal polling described to POLITICO showed Knight and Reps. Dana Rohrabacher and Mimi Walters — all of whom lost — narrowly leading their Democratic opponents at the end of the campaign. Not only did the GOP get crushed in California, the party also got taken by surprise by the intensity of the backlash in the nation’s largest state, where Republicans projected confidence nearly all year before watching Democrats flip a whopping six House districts — and possibly a seventh.

The nightmare results were the end result of a toxic brew of overconfidence and presidential unpopularity, as some Republicans failed to recognize and reckon with the unprecedented negative reaction to President Donald Trump in districts from Orange County to California’s agriculture-heavy Central Valley.

Republicans’ shock has only deepened weeks after Election Day, as absentee and provisional ballots boosted Democrat TJ Cox ahead of Rep. David Valadao, a moderate Central Valley Republican who had previously won at least 57 percent of the vote in good and bad years for the GOP, despite the fact that his party’s presidential candidates regularly lose his district by double digits.

Cox, who led by a 591 votes on Friday afternoon, declared victory earlier in the week, thanking supporters who believed in his bid “even when the outlook may have seemed dim.” (POLITICO still has the race uncalled.)

A Valadao loss would be no mere upset. Sixty-two other House races around the country drew more outside spending than Valadao’s, according to analysis by the Center for Responsive Politics, and Republican leaders saw Valadao — a known and respected quantity locally even during bad times for the GOP — as all but safe throughout much of the fall. The GOP threw only a relatively small amount of money into the district in the final week, with some describing it as an insurance measure.

Valadao’s struggles symbolize the depth of the Democratic wave, which could balloon to as big as a 40-seat House gain behind backlash to President Donald Trump.

Republicans projected confidence in California earlier this year — Walters told Fox News in June that Nancy Pelosi had “overplayed her hand” in the state, while National Republican Congressional Committee Chairman Steve Stivers told the Los Angeles Times that Walters didn’t want or need his committee’s help.

But Democrats saw the opportunity from the beginning, even in Valadao’s district. The Democratic Congressional Campaign Committee persuaded Cox to run against Valadao instead of campaigning in a district seen as more competitive — part of a broader, successful effort to back winners in the state’s all-party primaries and avoid getting “locked out” of battleground districts by the top-two primary system. The DCCC followed up in the fall by pumping TV ad money into Cox’s campaign while most outside groups left the district alone.

Now, while Republicans agree they’ve witnessed a wipeout — Republican National Committeeman Shawn Steel called the California election results “a nuclear political holocaust for Republicans” — they can’t agree why.

Evidence-free suggestions of fraud have multiplied, while other Republicans have focused on unprecedented Democratic campaign spending.

Rohrabacher told The San Francisco Chronicle that he “didn’t lose this vote, my district was purchased,” after Michael Bloomberg’s Independence USA PAC sank $4.4 million into his district, along with a smattering of other Democratic groups. Congressional Leadership Fund, a super PAC aligned with House GOP leadership, put in $4 million to shore up Rohrabacher, but he was already being vastly outspent.

Steel also blamed a wave of $91 million in outside spending that hit seven GOP-held seats, all of which Hillary Clinton carried in 2016.

“What we didn’t anticipate was the money tidal wave, and it’s pretty clear to me that the billionaires run the Democratic Party,” said Steel, who also wrote a Washington Examiner op-ed absolving Trump of responsibility for the losses.

But Valadao outraised and outspent his opponent. The more powerful factor was the state’s rejection of Republicans writ large, largely driven by distaste for President Donald Trump.

“If you were running for dogcatcher in Orange County – or in a lot of places in California – and you had an ‘R’ next to your name on the ballot, you lost,” said Andrew Acosta, a Democratic consultant in the state. “It was Trump. Trump created this. There wasn’t much Republicans could do to stop it.”

It could be decades before state Republicans’ chances recover, some in the party say.

“This is the death of the Republican Party” in California, said Mike Madrid, a Republican consultant in the state. “There’s no coming back from this for at least a generation, if not more.”

Still other Republicans pointed fingers at the campaigns themselves, arguing that none of the congressional campaigns “were any different than any other generic Republican, so that was the fundamental problem,” said John Thomas, a GOP consultant based in California. “Trump was underwater in all the other seats, except in Dana’s, so that was an easy argument for Democrats to make, vote out the generic Republicans.”

Rexroad, who worked on Knight’s campaign, said he’s still grappling with what happened, weighing whether the results hinged on tactics or on atmospherics.

“Honestly, I don’t know what we could’ve done,” he said. “I’m going to spend a lot of my time over the holidays thinking about it.”