Incumbent Rep. Mike Thompson, a 28-year veteran of California's 4th Congressional District and moderate Blue Dog Democrat, faces his strongest primary challenge in years from Eric Jones, a younger venture capitalist and nonprofit executive who has raised over $3.2 million. The June 2 top-two primary occurs in a district redrawn under Proposition 50, which added conservative-leaning counties and reduced the Democratic lean to a Harris margin of about 56 percent in 2024. Jones has drawn endorsements from progressive groups and self-funded significantly, while Thompson benefits from institutional support including Governor Newsom and the state Democratic Party. A fragmented Republican field of six candidates with minimal fundraising makes it unlikely any GOP contender reaches the top two, leaving trader consensus focused on Thompson and Jones advancing.