California’s congressional primaries on Tuesday are a preliminary test of Democrats’ best chance at countering Republican redistricting gains elsewhere this year.

FILE - In this Sept. 26, 2019, file photo, former Republican congressman Darrell Issa speaks during a news conference in El Cajon, Calif. Former California Republican U.S. Rep. Darrell Issa made a successful comeback bid and will return to Congress after defeating Democratic opponent Ammar Campa-Najjar. Issa gave up his seat two years ago and then ran this year in the neighboring 50th District anchored in San Diego County. The former nine-term congressman and ardent supporter of President Donald Trump trailed early in the San Diego-area 50th District. Issa ran this year in the neighboring and more conservative 50th District anchored in eastern San Diego County. Issa was among a group of Republican congressional candidates who fared well even though President Donald Trump was trounced in California by Democrat Joe Biden.