California's most powerful union boss allegedly extorted fellow labor leaders to back a billionaire tax and terrorized women who stood in his way — and the investigation says the claims hold up.

SEIU United Health Workers West President Dave Regan, the architect behind California's Proposition 40 wealth tax, demanded the SEIU state council endorse the measure by Jan. 1 or face consequences, according to an independent investigation commissioned by the national SEIU. The New York law firm Cohen, Weiss and Simon interviewed 18 current and former labor officials over nearly three months and substantiated most of the allegations against Regan, whose union is one of the state's most politically powerful forces.

This is the machine laid bare: a union boss who allegedly leveraged the threat of a Trump Labor Department investigation to force compliance, then turned on women who didn't fall in line.

Former SEIU California State Council President David Huerta told investigators that during a Dec. 3 conversation, Regan raised unspecified "governance issues" and demanded full endorsement of the billionaire tax. When Huerta asked if Regan intended to initiate an investigation, Regan replied: "I don't have to; there are others who would." Huerta said he left the conversation feeling "extorted." Investigators determined Regan likely suggested he could trigger scrutiny from the Trump administration's Department of Labor.

That same day, Regan delivered an even more direct threat to SEIU California Executive Director Tia Orr. According to her account, Regan told her "state council better endorse this measure by Jan. 1 or I'm coming for you." He later rode with her to the airport, sat beside her on the flight, and tapped his watch when they separated — a gesture she interpreted as a warning her time was running out.

The probes also found credible an allegation that Regan physically assaulted former SEIU executive director Courtni Pugh in 2009. Pugh now runs the consulting effort opposing the billionaire tax. State union officials have temporarily banned Regan from SEIU California offices to protect female employees.

Four labor officials, led by Huerta, filed the rare formal union charge against Regan in February. SEIU California spokesperson Christopher Calhoun stated that leaders filed charges "alleging a pattern of bullying, threats, abuse, harassment, physical violence and attempted extortion" and that initial investigations "substantiated most" of the claims.

Regan denied the allegations in an interview with the Los Angeles Times, calling them "internally contradictory, fundamentally biased, and maybe most importantly, politically motivated." He claimed the charges are retaliation for his advocacy of Proposition 40. But the law firm hired by the national union investigated that retaliation claim and found it could not be substantiated.

Regan's union went further, attacking the messenger. SEIU-UHW accused the Los Angeles Times of protecting the financial interests of its billionaire owner, Patrick Soon-Shiong. "It appears to be another case of a billionaire newspaper owner using his platform to protect himself and his friends," the union said in a statement. The New York Post highlighted this counterattack; the Times did not dwell on it.

So the defense is two-pronged: the allegations are political retaliation, and the newspaper covering them is a tool of a billionaire. Neither claim survived scrutiny. The extortion findings were substantiated. The retaliation claim was not. And the investigation was commissioned by Regan's own parent union.

The question now is whether California voters will know any of this before they vote on Proposition 40 in November — or whether the same political machine Regan built will keep the story buried.