The union leader spearheading California’s controversial billionaire tax proposal went on the offensive against Gov. Gavin Newsom, accusing the Democrat of cozying up to the ultra-rich as the pair clash over a last-ditch effort to keep the measure off the November ballot.

In a blistering interview with The Lever, Dave Regan, president of SEIU-United Healthcare Workers West, blasted Newsom’s opposition to the proposed tax, suggesting the governor’s stance is driven by political ambition rather than policy concerns.

“I think Governor Newsom probably can’t envision a successful campaign where he doesn’t accommodate the needs of the billionaire class,” he said.

Regan was referring to widespread speculation that Newsom is eyeing a 2028 White House run — a bid that would require raising massive sums of cash from wealthy donors.

He noted such a campaign could cost “hundreds of millions” of dollars.

“There’s a limited number of places where you’re able to do that,” Regan said.

The labor leader argued that Newsom’s alleged deference to billionaires could backfire on Democrats nationally and pave the way for the election of “Donald Trump’s protege” if the California governor ultimately secures the party’s presidential nomination.

“The right and the far right is actually, their rhetoric is more populist than the rhetoric of the Democrats,” Regan said. “That’s what I worry about, is we don’t need another president whose first priority is to take care of the wealthiest people in America.”

That remark was a veiled shot at Newsom, as President Trump has been routinely criticized by the governor and other liberals for “crony capitalism.”

🚨EXCLUSIVE: @Davidsirota interview with Dave Regan, the union leader spearheading California’s billionaire tax that @GavinNewsom and his billionaire allies are trying to kill.

Regan warns Democrats who keep catering to billionaires aren’t stopping Trumpism — they’re helping… pic.twitter.com/LUZqvsBtsD

— The Lever (@LeverNews) June 19, 2026

Newsom has publicly opposed the proposed one-time 5% tax on the state’s ultra-rich due to fears it could significantly hurt California’s economy after billionaires flee the state. He reportedly has made behind-the-scenes moves to isolate Regan by recruiting other unions and other unlikely allies to oppose the tax.

Supporters of the tax argue the revenue is needed to help offset federal health care cuts. The measure officially qualified for the November ballot this week, though it could still be withdrawn before June 25 if Newsom succeeds in negotiating a compromise.

So far, there hasn’t been much progress, at least publicly. On Thursday, supporters offered Newsom the option of a 2% tax enacted through legislation instead, but the governor swiftly declined.

“The governor supports making the wealthiest Americans pay their fair share, but this poorly designed state-only measure will defund teachers, schools, clinics, and public safety,” his office said.

If the proposal reaches voters, analysts expect an expensive election fight. Billionaires, including Google co-founder Sergey Brin, have already poured significant money into efforts to defeat the measure.

The Post reached out to Newsom’s office for comment on Regan’s remarks.