A Bay Area billionaire with family ties to Gov. Gavin Newsom’s wife has quietly turned up on donor reports for committees and candidates going after the governor, according to public filings and published reporting. The mix of seven-figure ballot spending and smaller, targeted campaign checks has dropped an unusual family subplot into California’s already crowded governor’s primary and reminded local voters just how far outside money can travel in state politics.
Siebel’s political spending in California
Tom Siebel, the Woodside tech founder behind Siebel Systems and C3.ai, has emerged as a high-profile political donor in recent years. According to CalMatters and California Fair Political Practices Commission records, Siebel put $1 million into a committee opposing Proposition 50 in 2025.
Local coverage has also connected him to a high-dollar Trump fundraiser in Woodside that sold host-committee slots for six-figure prices, providing a glimpse of his national and statewide giving habits. That event was detailed by Palo Alto Online, alongside FPPC filings archived online.
Small donations flagged by the New York Post
The New York Post reported today that Siebel has also written smaller, direct checks to two gubernatorial hopefuls: about $50,000 to San Jose Mayor Matt Mahan and $10,000 to Steve Hilton. Those specific dollar amounts come from the Post’s reporting.
Public biographical records also trace a family connection between Siebel and the governor’s wife, Jennifer Siebel Newsom, a detail reflected in profiles such as her entry on Wikipedia.
How the candidates fit
Steve Hilton, a conservative commentator running as a Republican, has made Newsom his favorite target on the trail, repeatedly blasting the governor and calling his stewardship of California a total disaster in recent interviews. According to coverage in the Washington Examiner, those attacks on Newsom have become a central theme of Hilton’s campaign.
On the other side of the field, San Jose Mayor Matt Mahan, a Democrat, has drawn in a roster of deep-pocketed Bay Area backers and aligned independent committees. His fundraising pattern has been tracked and dissected by the San Francisco Chronicle.
Why this matters for the June primary
Outside money can pay for ads, polling, opposition research and staff that boost lesser-known candidates into the statewide spotlight, sometimes reshaping the top-two primary lineup in the process. Polling averages and recent surveys place Hilton near the top of the field in many trackers, which could magnify the impact of any outside dollars that end up backing his run, according to polling compilations and aggregations of recent surveys. Those trends are summarized on the 2026 governor’s election polling pages that collect recent averages and margins.
The story is still developing. Campaign committee reports and state disclosures will keep rolling out in the days ahead, revealing more checks, ad buys and outside spending. We will be watching those public filings and local coverage to see whether Siebel-linked money ultimately shows up as television spots, digital ads or other independent efforts aimed at Newsom.
