Republican former members of Congress who were swept out of office in 2018 are trying to get back on the stage, including Darrell Issa of San Diego. Mr. Issa, who declined to seek re-election in 2018 in the face of a strong Democratic challenge, has decided to run this year for a different seat, the one held until recently by a fellow Republican, Duncan Hunter, who resigned after pleading guilty to using campaign funds for personal expenses.

In Mr. Hunter’s old district, Randy Birrenkott, 70, said he knows many neighbors who became disgusted with California’s liberal politics and moved to places like Texas or Montana. “Right now it’s a strong conservative district, but it’s slowly going down,” he said.

California is not the only state whose political complexity is often overlooked in the shorthand of a polarized era. New York as a whole is overwhelmingly Democratic, but upstate New York and the New York City borough of Staten Island are as Republican as parts of Central California are.

New York Democrats like Chuck Schumer, the Senate minority leader, and Jerrold Nadler, the chairman of the House Judiciary Committee, have played important roles in the impeachment drama. But with Mr. Schiff, Ms. Pelosi, Mr. McCarthy and Mr. Nunes at the forefront of the daily battles in Washington, no other state has become quite as identified with the impeachment battle as California has.

The Republican Party is hobbled in California, and many moderate Republicans believe it will only become less influential in years ahead. The party has been on a steady decline for nearly 20 years in the state, where Richard M. Nixon was born and where Ronald Reagan was one of its most successful governors.

There are now more independent voters in California than registered Republicans. The G.O.P. does not hold a single statewide office, and is vastly outnumbered in the legislature. While the effort to recall Mr. Newsom has the support of Republican leaders, it is unlikely to gain enough signatures to qualify for the ballot. or enough support to win the approval of voters if it did.

Republican moderates — who were once a major force in the party, particularly when Arnold Schwarzenegger, a Republican, was governor — have been marginalized.