The California Democratic Party voted Sunday to officially endorse Proposition 40, a controversial billionaire wealth tax set for the November ballot, defying Governor Gavin Newsom and other top state officials who oppose the measure.

The endorsement from the state party's executive committee puts California Democrats on a collision course with their own leadership over what could become the nation's first wealth tax. Proposition 40, known as the 2026 Billionaire Tax Act, would impose a one-time 5 percent tax on the net worth of California billionaires.

What the Tax Would Do

The ballot initiative targets an estimated 200 billionaires residing in California, though some wealth advisers believe the actual number could be higher. Revenues from the tax would be directed toward offsetting federal cuts to Medi-Cal and other social programs, according to backers.

Unlike traditional income taxes, Proposition 40 would assess net worth directly, creating what supporters call a long-overdue wealth tax on the ultra-rich. The measure describes itself as a temporary, one-time levy, though critics warn it could establish precedent for recurring wealth taxation.

Tax Foundation experts have raised questions about enforcement and constitutionality, noting that California's tax code is already heavily dependent on receipts from wealthy individuals. Any capital flight triggered by the tax could reduce regular state revenues, opponents argue.

Internal Democratic Split

The state party's endorsement directly contradicts the positions of Governor Newsom and U.S. Health and Human Services Secretary Xavier Becerra, both California Democrats who have expressed concerns about the economic impact and feasibility of the tax.

Labor groups are similarly divided. While some unions have thrown their support behind the measure, others worry about unintended consequences for California's business climate and state budget stability.

The push for Proposition 40 has been led by union organizers known for using ballot initiatives as leverage against powerful interests. These activists view the billionaire tax as a way to force negotiations over funding priorities and counter what they see as a state tax system tilted toward the wealthy.

November Showdown Looms

With the Democratic Party endorsement secured, Proposition 40 gains crucial institutional support heading into the fall campaign. Opponents, including business groups and fiscal watchdogs, are expected to mount a well-funded effort to defeat the measure.

California voters will decide the fate of the billionaire tax on November 3, 2026. If approved, the state would break new ground in American taxation, implementing a wealth levy that no other state has successfully enacted.

The outcome could shape national debates over progressive taxation and wealth inequality, with other Democratic-led states watching California's experiment closely. For now, the Democratic Party establishment finds itself at odds with its own grassroots over how far left the state should go on taxing the rich.