**Proposition 39**, a citizen-initiated constitutional amendment on the November 3, 2026 ballot, would require government-issued photo ID for in-person voting and the last four digits of such an ID for mail ballots, while directing officials to use government data for citizenship verification on voter rolls. It qualified in April 2026 after proponents submitted over 1.3 million signatures. Backed by Republican legislators including Carl DeMaio and funded heavily by out-of-state conservative donors, the measure has drawn substantial campaign spending on both sides amid high voter interest. California’s Democratic registration edge and organized opposition from groups like the ACLU and League of Women Voters create headwinds, though the free state-issued ID provision and broader national debates over election procedures have kept trader-implied odds near even. Recent polls show the contest remaining tight weeks before Election Day.