California redistricting pits GOP incumbents Ken Calvert and Young Kim against each other

Redistricting has turned two long-serving California Republicans into direct rivals, and both are now trying to prove who is closer to Donald Trump. Ken Calvert and Young Kim, pressed by a newly redrawn map, have attacked each other as insufficiently MAGA in California Congressional District 40, a seat that stretches across parts of Orange County and Riverside County and has become one of the last Republican-controlled House districts in Southern California.

The collision grew out of Proposition 50, which California voters approved in the November 4, 2025 special statewide election. The measure temporarily replaced the state’s independent congressional map with legislatively drawn districts from 2026 through 2030, reshaping several GOP-held seats and forcing incumbents to adapt to a very different political terrain. The June 3, 2026 primary will be the first held under the new maps.

Calvert, who has served in Congress since 1993, announced on November 5, 2025 that he would seek reelection in the new 40th District rather than remain in a seat that had become more Democratic. That decision set up a direct clash with Kim, who has served in the U.S. House since 2021 and has represented the 40th District since 2023. In a state where Democrats used redistricting to make several Republican seats harder to hold, the two incumbents are now fighting not just for a nomination but for the right to define the Republican Party in a district newly drawn to test them.

The race has turned personal. Calvert’s side has called Kim a “Trump traitor” and a “RINO,” shorthand meant to cast her as insufficiently loyal to the former president and to the party’s hard-right base. Kim’s campaign has answered with polling that it says shows her leading Calvert overall and among key Republican blocs, an effort to argue that the younger incumbent has the broader path to survival in a sharply altered electorate.

That ideological squeeze is the larger story of the district. California’s redistricting did not just redraw borders; it changed incentives. In a seat where the primary electorate matters more than ever, both candidates are being pushed toward harder-line positioning as they compete for a base that will decide the nomination before a likely competitive general election. In Southern California, where Republicans have already lost ground, the new map has made loyalty to Trump and the MAGA brand a currency of survival.