Who's In the Race

California's 4th Congressional District features Democratic incumbent Rep. Mike Thompson (D-CA) and Democratic challenger Eric Jones in the Nov. 3 general election. Both candidates are Democrats, a result of California's top-two primary system, which advances the two highest vote-getters regardless of party. ​

Thompson has served in Congress since 1999 and is a Vietnam combat veteran who served in the U.S. Army as a staff sergeant and platoon leader; he previously served in the California State Senate. He won the June 2 top-two primary with about 41% of the vote, about 19 percentage points ahead of Jones, who finished second with about 22%. Jones grew up in rural Maine in a family that relied on food stamps, Medicaid and disability benefits; he says he attended Yale University on a full scholarship and later built health-care and financial-inclusion businesses. He now leads nonprofit work in Napa. Jones advanced from the primary with about 22%, edging the top Republican, Ray Riehle, by just 1.5 percentage points.

What They Stand For

Thompson has supported improving and extending the Affordable Care Act, according to his official House website. He has also supported Medicare negotiating prescription-drug prices and lowering seniors' out-of-pocket costs, including expanded telehealth access, expanding background checks for firearm sales and most transfers, while protecting law-abiding gun owners' Second Amendment rights, land conservation, action to prevent climate change and a transition to a clean-energy economy; and requiring data centers to pay for the water and electricity they use, and ensuring development does not displace agricultural land.

Jones has proposed 12-year term limits, a ban on congressional stock trading and an end to corporate and special-interest money in politics, according to his campaign website. He has also proposed expanding Medicare to cover vision, dental, hearing and in-home care, and lowering prescription-drug costs through negotiation, ending PG&E's monopoly, allowing municipal utility providers and strengthening federal oversight of the utility, investing in California water infrastructure, protecting family farms and public lands, and creating a first-time homebuyer zero-down mortgage program; and banning data centers in California, as well as restricting social media and artificial intelligence use by children under 16.

The Money Behind the Race

Through June 30, Jones had raised about $8.4 million in total receipts, roughly twice Thompson's $4.2 million, but Thompson, the incumbent, held about $1.1 million in cash on hand compared with Jones's $656,000. Outside groups have spent about $1.9 million supporting Thompson and about $1.5 million opposing him, while spending about $1.2 million supporting Jones and about $1.3 million opposing him, according to FEC outside-spending records; BDA PAC is the largest spender supporting Thompson (about $1.31 million) and opposing Jones (about $1.31 million), while NEW LEADERSHIP NOW is the largest spender opposing Thompson (about $1.46 million) and supporting Jones (about $1.23 million).

Race Outlook: Ratings and Betting Markets

Cook Political Report rated the race "Solid Democratic" as of Oct. 19; Sabato's Crystal Ball rated it "Solid Democratic" as of Oct. 11; and Inside Elections rated it "Solid Democratic" as of Oct. 2. On Kalshi, traders gave Thompson a 76.5% chance of winning, as of Oct. 21.

Thompson won the district with about 66% in 2024 and about 68% in 2022, a decline of about 1.3 percentage points between those two cycles. Kamala Harris carried California in the 2024 presidential election with about 58% of the vote.

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