Newsom's Billionaire Cousin Funds Rivals Mahan and Hilton

Tech mogul Tom Siebel, second cousin of the governor's wife, backs two of Gavin Newsom's biggest critics in California governor's race.

Apr. 17, 2026 at 9:07pm

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A dimly lit, cinematic painting of an empty government office or campaign headquarters, with warm sunlight streaming through the windows and deep shadows casting across the room, conveying a sense of solitude and contemplation around the political dynamics at play.The family feud over California's gubernatorial race highlights the outsized influence of wealthy donors, even against their own relatives.San Jose Today

A billionaire cousin of California Governor Gavin Newsom's wife, Jennifer Siebel Newsom, is using his vast tech fortune to support two of the governor's most vocal critics in the race for California governor. Tom Siebel, founder of Siebel Systems, has donated $50,000 to San Jose Mayor Matt Mahan's campaign and $10,000 to Republican Steve Hilton, a former Fox News host who has harshly criticized Newsom's performance as governor.

Why it matters

This family feud highlights the deep divisions within the California political landscape, as a wealthy tech mogul leverages his resources to back candidates opposed to the sitting governor, who also happens to be his second cousin. The donations raise questions about the role of money in state politics and the influence that wealthy individuals can wield, even against their own relatives.

The details

Siebel, who sold his enterprise software firm Siebel Systems to Oracle for $5.8 billion in 2006, has an estimated net worth of around $4 billion. He has a history of political donations that have put him at odds with his famous cousins, including a $1 million contribution to the campaign against Prop. 50, Newsom's successful effort to gerrymander California's congressional maps. Siebel has also donated $500,000 to former President Donald Trump's 2024 campaign.

  • Siebel donated $50,000 to Matt Mahan's gubernatorial campaign.
  • Siebel donated $10,000 to Steve Hilton's gubernatorial campaign.

The players

Tom Siebel

A billionaire tech mogul and founder of Siebel Systems, who is the second cousin of California Governor Gavin Newsom's wife, Jennifer Siebel Newsom.

Matt Mahan

The mayor of San Jose, California, who is running for governor and has clashed with Newsom in the past over homelessness policy.

Steve Hilton

A former Fox News host who is running for California governor and has been one of Newsom's harshest critics, giving the governor an 'F' grade for his performance.

Gavin Newsom

The current governor of California, who is the cousin-in-law of billionaire tech mogul Tom Siebel.

Jennifer Siebel Newsom

The wife of California Governor Gavin Newsom and second cousin of billionaire tech mogul Tom Siebel.

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What they’re saying

“'F, the lowest possible. It's a total disaster.'”

— Steve Hilton, Gubernatorial Candidate

What’s next

The California gubernatorial race is expected to be highly competitive, with Mahan and Hilton's campaigns receiving significant funding from Siebel likely to draw increased scrutiny and attention in the months leading up to the election.

The takeaway

This family feud over the California governor's race highlights the outsized influence that wealthy individuals can wield in state politics, even against their own relatives. The donations from Siebel to Newsom's critics raise questions about the role of money in shaping the political landscape and the need for greater transparency and accountability in campaign finance.