Republican Rep. Ed Royce is out. Democrats’ chances to flip Orange County seat just got better. | The Sacramento Bee

Orange County Congressman Ed Royce, a targeted Republican, announced Monday he will not run for re-election in one of several seats Democrats hope to capture in 2018.

Royce holds one of 10 House Republican-held seats in California targeted by the Democratic Congressional Campaign Committee this year. His decision to not seek re-election could be an ominous sign for California Republicans, seen as crucial in the GOP battle to retain the House.

Royce, chairman of the House Foreign Affairs Committee, did not say explicitly why he’s not running. First elected in 1992, Royce is termed out of his committee chairmanship this year. He said his focus for the remainder of his term will be key issues, including Russian interference in American elections.

“In this final year of my Foreign Affairs Committee chairmanship, I want to focus fully on the urgent threats facing our nation, including the brutal, corrupt and dangerous regimes in Pyongyang and Tehran, Vladimir Putin’s continued efforts to weaponize information to fracture western democracies, and growing terrorist threats in African and Central Asia,” Royce said in a statement.

Since President Donald Trump took office, Republicans have come under fire at town halls and other public events for backing high-profile GOP priorities, including repealing Obamacare, stemming the flow of immigrants into the country and overhauling the U.S. tax code. A December poll from UC Berkeley’s Institute of Governmental Studies showed 51 percent of Californians oppose the recently passed tax bill, with 30 percent in support.

Though the 39th Congressional District is conservative and long seen as a Republican stronghold, Royce’s departure could be a good sign for Democrats. The Cook Political Report on Monday immediately shifted the seat to one that “leans Democratic,” from the previous “lean Republican.”

The ranking by Sabato’s Crystal Ball, at the University of Virginia’s Center for Politics, also changed Monday with Royce’s announcement. It’s now seen as a Republican “toss-up.” Previously, it was ranked as “likely Republican.”

Royce easily won re-election in 2016, but Orange County – and California as a whole – is growing increasingly Democratic. The 39th District is one of seven Republican-held congressional districts clustered in the Central Valley and Orange County where voters chose Hillary Clinton over Donald Trump for president. Voters in Royce’s district went for Clinton by more than 8 percentage points.

Democratic strategists and campaign backers said Royce’s decision reflects voter angst directed at Republicans.

“Facing strong, well-funded Democratic challengers, a historic investment in Orange County by the DCCC, and a failed Republican agenda of raising taxes on working families and trying to rip health care away from millions of California, Congressman Ed Royce’s retirement is another sign of Democrats’ growing momentum in 2018,” said DCCC spokesman Drew Godinich.

Eddie Kurtz, executive director of the left-leaning Courage Campaign, also painted Royce’s announcement as a reflection of the political danger ahead for California Republicans.

“Rep. Royce knows that if he ran for re-election in 2018, he would lose,” Kurtz said in a statement, adding that it is “proof positive that Democrats are gaining momentum and ready to retake the House in 2018 with a wave election ... Let this be a clear message to all remaining members of California’s Republican congressional delegation: Your days are numbered, and come November, you will be out of a job.”

Steve Stivers, chairman of the National Republican Congressional Committee, said in a statement that, “Republicans are fired up and ready to hold this seat.

“Orange County has no shortage of Republican talent and a highly organized ground effort with the NRCC at the forefront,” Stivers said. “We have just one message for Democrats who think they can compete for this seat: Bring it on.”

Other Republicans could be in political danger this year.

Rep. Mimi Walters, R-Laguna Niguel, also represents an Orange County district that went for Clinton over Trump. The district is now ranked by Sabato’s Crystal Ball as “leans Republican.” It was changed last year from “likely Republican.”

Other targeted Republicans include Reps. Darrell Issa, R-Vista; Devin Nunes, R-Tulare; Dana Rohrabacher, R-Costa Mesa; Steve Knight, R-Palmdale; David Valadao, R-Hanford; Jeff Denham, R-Turlock; Duncan Hunter, R-Alpine; and Tom McClintock, R-Elk Grove.

The NRCC is targeting four Democrats: Reps. Ami Bera, D-Elk Grove; Salud Carbajal, D-Santa Barbara; Raul Ruiz, D-Palm Desert; and Scott Peters, D-La Jolla.