California’s Proposition 40 would impose a one-time 5% tax on all billionaires in the state if more than 50% of voters fill in the box for “yes” by Tuesday. It’s going to be a close one and may not pass, based on the latest polling.

Back in May, the Public Policy Institute of California found that 54% of California voters said they supported the wealth tax, with 45% saying they’d vote no.

The more recent polling has shown it to be even closer, with a Public Policy Institute of California poll taken Oct. 16-22 showing just 46% saying they would vote yes and 52% voting no.

An even more recent poll by a different organization, the University of California Berkeley Institute of Governmental Studies, taken Oct. 19-25, shows just 42% saying they’ll vote yes and 50% pledging to vote no.

Why the big shift? That could have something to do with the massive amounts of money that billionaires are spending to fight the proposed tax. Building a Better California, funded by Google’s Sergey Brin, Eric Schmidt, and several other billionaires, have outspent those who are trying to get Proposition 40 passed 250-1, according to the Washington Post.

Building a Better California has raised $379 million and spent about $148 million, according to the Post. And if you watch TV in California, the ads are everywhere. Their main pitch is that passing Prop 40 will potentially allow legislators in California to tax non-billionaires in the future.

If Prop 40 passes, about 90% of the money is supposed to be allocated to Medi-Cal, the name for Medicaid benefits in California, according to KQED. The remaining 10% would go toward food assistance and education-related programs. Those are worthy goals, of course, given the way that President Donald Trump’s administration has taken a chainsaw to health care benefits and programs to feed the hungry since his return to power.

Opponents of Prop 40 have successfully gotten two of their own propositions on the ballot, Proposition 41 and 42, which are essentially poison pills that would negate Prop 40 if it does pass. Prop 41 is also close, with a recent poll from the Public Policy Institute of California showing 49% for no and 48% for yes. The same pollster has Prop 42 at 51% yes and 47% no.

Prop 40 isn’t strictly a partisan issue, at least when it comes to how establishment Democrats in California view it. Gov. Gavin Newsom, who is termed out and will be leaving office in January 2027, opposes the billionaire tax. So does Democratic gubernatorial candidate Xavier Becerra, who’s polling way ahead of Republican candidate and former Fox News host Steve Hilton.

Newsom and Becerra argue that California’s economy will suffer if the billionaires leave, though there’s no evidence that a mass exodus would actually occur. Millionaires threatened to leave New York if Zohran Mamdani was elected mayor. But historically this has always been an empty threat. The wealthy have the means to absorb tax increases. The people who are most likely to leave expensive places like California and New York are the poorest over affordability concerns.

California has about 200 billionaires who would be affected if the one-time tax passes, according to the San Jose Spotlight. While some big names have come out against it, there’s at least one billionaire who doesn’t object to paying billions in taxes: Nvidia’s Jensen Huang, worth $170 billion.

“The fact that I can afford to pay $8 billion in taxes over five years is a privilege,” Huang recently told CBS Sunday Morning. “I’m not afraid of paying taxes. I’m just afraid of being poor.”Obviously it’s wise to take any poll with a grain of salt. Californians will soon decide whether to impose a one-time tax on billionaires and guys like Meta CEO Mark Zuckerberg are threatening to move out of the state if Prop 40 passes. We may soon get the chance to see if Zuck keeps his word.