California's 4th District Primary

When Californians head to the polls on November 3, voters in the state's 4th Congressional District will face an unusual choice: two candidates from the same party. Incumbent Democratic Rep. Mike Thompson and Democratic challenger Eric Jones are the only two names on the November ballot for this House seat.

California uses a "top-two" primary system, sometimes called a jungle primary, in which all candidates from all parties compete on a single June ballot. The top two advance to the general election, regardless of party (the June 2 primary did draw nine candidates across the Democratic, Republican, Independent, and other party lines, but Thompson and Jones claimed those two spots).

Thompson finished first with 84,753 votes, or about 41 percent of the total primary vote. Eric Jones finished second with 45,992 votes, or roughly 22 percent. Together, the two Democrats accounted for nearly two-thirds of all votes cast in the primary. That kind of Democratic dominance in the primary is consistent with how the CA-4 congressional race has performed in recent election cycles. The district, which covers portions of Northern California including parts of the Napa Valley wine country and surrounding communities, has long been reliably Democratic territory.

The Candidates

Thompson has represented California's fourth congressional district in the House since 1999 and is a member of the House Committee on Ways and Means. He grew up in a working-class family as the grandson of Italian immigrants, and dropped out of high school to enlist in the Army and serve in the Vietnam War as a staff sergeant and platoon leader. After later returning to school, he became a first-generation college graduate from CSU, Chico.

Jones grew up in a military family in small-town Maine and was also a first-generation college graduate from Yale University, where he attended with a full scholarship. He has no prior congressional experience but co-founded a with his wife called the Eric and Rachel Jones Foundation. Jones also founded the American Dream Institute, a nonprofit dedicated to the protection of free speech online.

The Money Behind the Race

Outside spending in the CA-4 congressional race has been substantial by House primary standards. Total outside spending in the race reached approximately $2.81 million as of mid-June 2026, according to FEC data. The top outside spender was a group called New Leadership Now, which reported spending roughly $1.56 million. A group called BDA PAC reported spending approximately $1.2 million. Smaller amounts were reported by Article One PAC, the California Leadership Fund, and others.

Ratings vs Odds

Every major political ratings organization that tracks congressional races has classified this seat as "solid Democratic." Cook Political Report, Sabato's Crystal Ball, and Inside Elections all issued "solid Democratic" ratings for this race as of mid-June.

On the prediction markets, Kalshi showed Democrats with a 98 percent probability of winning the seat as of July 10. Given that both certified nominees are Democrats, the real question is which will take the seat. As of July 10, 1,192 contracts had been traded on this race on Kalshi, a relatively small volume that reflects general certainty about the outcome.

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