"He didn't just vote for the bill, he spiked the ball afterwards," says Shawn Steel, a state Republican Party leader now gunning for Mayes.

"He’s obviously the happiest one of the four," Steel sneered. AB 398 extends California's cap-and-trade system for controlling greenhouse gas emissions through 2030.

Brown, who has become an outspoken critic of Donald Trump's climate change skepticism, pulled out the all the stops to get a two-thirds vote on the bill. And he couldn't have done it without Mayes, who voted for the measure and brought along six of his Assembly colleagues. Now the 42-year-old Republican from San Bernardino County may soon pay for it.

"It boils down to leadership," Steel says. "He voted against his own caucus. Leaders don’t do that."

Steel, who is a Republican National Committeeman for California and former state party chair, is helping to orchestrate the coup.

"What’s the point of being a Republican if you’re just going to be a Democrat-lite?" Steel asks. "His conduct is embarrassing."

Since the July vote heard round the state, Steel and his RNC partner, Harmeet Dhillon, have been coordinating the condemnation of Mayes county by county. So far, Republicans in more than a dozen counties have voted to support ousting Mayes.

"The Republican Party is a big-tent party," says Harmeet Dhillon, "but we all share some core principles, foremost among them being commitment to lower taxes and smaller government at all levels." AB 398, she says, "violates both fundamental principles."

Dhillon and Steel are especially incensed that Mayes's action gave political cover to three Assembly Democrats who didn't support the legislation. Republicans, said Dhillon, depend on the party to "hold a firm line against tax-and-spend gluttony in Sacramento."

Mayes insists he did the right thing and that being at the table improved the bill. "By bringing a market-driven approach to curbing greenhouse gases, this plan will reduce regulation, lower costs, cut taxes, protect jobs and provide a model for other states," Mayes wrote in a column published in the Sacramento Bee.

But Dhillon isn't buying it. "Chad fell for the flimflam because he is not a good negotiator," she said.

Not all Republicans share the view that Mayes is a Benedict Arnold-style traitor. Veteran GOP strategist Sean Walsh thinks the move to boot Mayes is "bad politics."

"It sends a signal that the party’s not organized, it’s not disciplined and it’s fighting among itself," Walsh says. "It hurts very badly from a funding raising, organizational and trust perspective."

Walsh, echoing Mayes and other Republicans who voted for the bill, says if AB 398 hadn't passed, it would have hurt businesses worse than this legislation.

"The California Air Resources Board would have raised fees," says Walsh, adding "that would be far worse than a cap-and-trade system where there’s flexibility."

Walsh, who advised Gov. Pete Wilson and many other Republicans, says his party should focus on knocking off vulnerable Democrats in the Legislature instead of trying to knock off one of their own.

"Already there’s a headwind in California against Republicans based on what Mr. Trump has done," Walsh says. "We don’t need to create more headwinds within the state."

Mayes' fate could be decided as early as Monday if Assembly Republicans caucus and vote on whether to keep their leader or elect a new one. Assemblywoman Melissa Melendez of Lake Elsinore is openly running to replace Mayes. Others, including Jay Obernolte (R-Big Bear Lake), may also seek to become the new GOP Assembly leader.