CALIFORNIA — Service Employees International Union-United Healthcare Workers West submitted nearly 1.6 million signatures to qualify a proposed one-time 5% tax on California billionaires' assets for the November ballot. The figure is roughly twice the 870,000 signatures required for ballot qualification.

The measure would impose a 5% tax on assets over $1 billion and would apply retroactively to billionaires living in California as of January 1. Backers estimate the tax would generate roughly $100 billion to backfill federal healthcare funding cuts signed by President Donald Trump last year. California has more billionaires than any other state, with a few hundred by some estimates, and nearly half of the state's personal income tax revenue comes from the top 1% of earners.

"Most Californians and most billionaires recognize how reasonable and necessary this proposal is — both to keep emergency rooms open and to save California businesses from closing," said Suzanne Jimenez, chief of staff of SEIU-United Healthcare Workers West. She also said the tax would "keep emergency rooms open, hospitals staffed and health care systems functioning." SEIU-United Healthcare Workers West considers the threat of a billionaire exodus to be exaggerated.

Tech leaders and Governor Gavin Newsom have condemned the proposal and vowed to stop it from passing. Newsom, who has long opposed state-level wealth taxes on the grounds that they would disadvantage California's economy, said he would "do what I have to do to protect the state."

Current and former chief executives from Google, DoorDash, Reddit, LinkedIn and Facebook have donated money to oppose the tax. Sergey Brin has donated at least $45 million to the Super PAC Building a Better California, and Eric Schmidt donated more than $3 million to the campaign opposing the measure. Larry Page spent about $173 million on two Miami mansions this year and has moved several of his limited liability companies out of California, while Mark Zuckerberg purchased a $170 million Miami property this year. The California Business Roundtable, led by donors including Page and Peter Thiel, is leading efforts to defeat the measure.

"It's one of the reasons why Newsom's path to the Democratic nomination is not going to be an easy one … and in the years to come, a billionaires tax that could backfire badly," said Jack Pitney, a political scientist at Claremont McKenna College.