SACRAMENTO, Calif. (Diya TV) — Gov. Gavin Newsom endorsed Proposition 42 on Friday, supporting a constitutional amendment that would prohibit new state taxes on personal assets and could override California’s proposed billionaire tax.

Google co-founder Sergey Brin helped finance the measure, which would ban new taxes on assets including business interests, investments and retirement accounts. It would also prohibit certain retroactive taxes.

Proposition 42 could invalidate conflicting measures on the same ballot if it passes and receives more affirmative votes. That provision could block Proposition 40 even if voters approve both proposals.

Proposition 40 would impose a one-time tax of up to five percent on covered assets held by qualifying billionaires. It would allocate ninety percent of the revenue to health care and the remainder to food assistance or education programs.

The proposed tax excludes real estate and some pension and retirement accounts. State analysts estimate it could raise tens of billions of dollars over several years, while potentially reducing future income-tax collections from billionaires.

Newsom said his endorsement would protect Californians’ retirement funds and life savings. Police and fire unions also support Proposition 42.

Critics dispute the campaign’s emphasis on ordinary retirement savings, noting that no active proposal would tax those accounts as supporters describe.

Service Employees International Union-United Healthcare Workers West, which backs the billionaire tax, criticized Newsom’s decision. Union vice president Debru Carthan argued that the governor was siding with wealthy donors at the expense of health care funding.

The California Democratic Party has endorsed Proposition 40, putting Newsom at odds with his party on the measure.

Newsom has opposed state-level wealth taxes, arguing that they could drive wealthy residents out of California and reduce income-tax revenue. He has instead proposed a national approach to taxing substantial wealth.

His spokesperson said he had not yet taken a position on Proposition 41, another Brin-backed measure that would impose spending limits and audit requirements on new state tax revenue.

Californians will vote on the measures in the Nov. 3 general election.