California's 48th Congressional District held its June 2, 2026, primary under a top-two system after Proposition 50 redistricting added suburban Democratic voters from San Diego and Palm Springs areas, shifting the formerly Republican-leaning seat into a more competitive position. Incumbent Darrell Issa retired, prompting Republican Jim Desmond, a San Diego County supervisor, to enter and secure strong party backing. He led results with over 40 percent of the vote. Democrat Marni von Wilpert, a San Diego city councilmember, placed second at roughly 19.5 percent and advances alongside Desmond to the November general election, ahead of other Democratic contenders including Ammar Campa-Najjar. These outcomes reflect vote consolidation dynamics and the district's altered partisan makeup heading into the general.