California election officials and ballot-measure campaigns escalated their advertising and voter-outreach efforts on Wednesday, as early voting gathered pace on a November slate dominated by five competing tax measures. The California Secretary of State's office reported rising mail-ballot returns across major counties.

The measures include proposals affecting property taxes, business levies and bond financing, and have drawn tens of millions of dollars in spending from both corporate interests and labour-backed coalitions. The California Taxpayers Association and the California Labor Federation have each mounted competing campaigns, according to filings with the state's Fair Political Practices Commission.

Polling released this week by the Public Policy Institute of California showed voters undecided on several of the measures, with support softest for revenue-raising proposals. The institute attributed the hesitancy to economic anxiety, finding that voters prioritise a functioning economy over new taxation.

Governor Gavin Newsom and Democratic legislative leaders have backed the bond-financing elements while declining to endorse the broader tax package, reflecting caution about voter fatigue. Republican lawmakers and business groups urged rejection of the measures, warning of added costs for employers and homeowners.

The outcome will shape California's fiscal trajectory as the state confronts budget pressures. County registrars said turnout patterns in the coming weeks would determine whether the revenue measures survive a sceptical electorate.