SACRAMENTO — Two days after Assembly Republican leader Chad Mayes supported California Democrats in renewing a key climate change policy, he’s facing calls to step down and accusations of having an extramarital affair with his predecessor.

Southern California conservative activist Joseph Turner published a blog post Sunday accusing Mayes of having an affair with Kristin Olsen, a former state assemblywoman who led the chamber’s Republicans for 14 months in 2014 and 2015.

Turner’s post included an April letter from Olsen’s estranged husband, Rod, to the Assembly requesting an investigation into whether any state resources were used to conceal a relationship between his wife and Mayes.

Rod Olsen confirmed the authenticity of the letter in an interview on Wednesday, saying he sent it in a moment of anger and retracted his request for an investigation hours later. “I was upset,” he said.

The letter was received by the office of Assembly Speaker Anthony Rendon, D-Paramount, and referred to the Assembly ethics committee, Rendon spokesman Kevin Liao said in an email. All ethics committee records are confidential, Liao said.

Mayes, 40, and Kristin Olsen, 43, declined to discuss the allegations. “This is a private matter and we’re not commenting on it,” said Matt Mahon, a spokesman for Mayes. “It’s a private matter, and I need to respect my family’s privacy,” Olsen, now a Stanislaus County supervisor and vice-chair of the California Republican Party, told the Sacramento Bee in a text message.

In the letter, Rod Olsen accused Mayes of using state funds to conceal the affair. (An earlier version of this article said incorrectly that Olsen had accused his wife of misusing funds.) “Specifically, I believe that Sergeants, staff, travel within the state, lodging, per diem, etc. were used at times by Assembly Member Mayes to foster and conceal this relationship from the public,” he wrote. “As you know, it is the obligation of every legislative member to be a good steward of taxpayer dollars, and I believe the committee will uncover that Mayes misused these funds, and acted unethically and in a manner unbecoming of a member of the California State Assembly.”

Mayes filed for divorce from his wife last month in San Bernardino County Superior Court, and the Olsens filed for divorce in April in Stanislaus County Superior Court, according to court records.

While rumors of the alleged affair had been swirling in Sacramento long before Turner’s blog post, the story didn’t surface publicly until the throes of high-stakes negotiations over the state’s cap-and-trade policy. Mayes and seven other Republican lawmakers were instrumental in passing legislation extending the program through 2030. Without GOP support, the bill extending cap-and-trade would not have received the required two-thirds vote in the Assembly on Monday night.

At least one Republican Party official publicly called on Mayes to step down because of his role in the cap-and-trade deal.

“He should resign or be replaced as the Assembly minority leader because of his conduct of delivering many votes for the disastrous tax increase that is the cap-and-trade bill,” Harmeet Dhillon, a Republican national commiteewoman for California, said in an interview Wednesday. “That is political malpractice.”

Dhillon, a San Francisco attorney who declined to comment on the affair allegations, said there was “a widely held view” among the Republican Assembly caucus that Mayes should not be minority leader and that multiple potential candidates to replace him were already “counting their votes.”

Other state Republicans, however, criticized the accusations against Mayes.

It’s “disgusting that personal attacks would be made against elected officials because of policy votes – regardless of animosity against the vote,” Kevin Spillane, a Republican consultant in Sacramento, wrote on Twitter.

Disgusting that personal attacks would be made against elected officials because of policy votes – regardless of animosity against the vote. — Kevin Spillane (@SpillaneCa) July 19, 2017

In an interview with the Mercury News and East Bay Times, Turner, who runs an group called American Children First, said he didn’t intentionally post the letter to disrupt the cap-and-trade deal, but that he has wanted to “take a run at (Mayes) for a while.”

“I think he’s a horribly ineffective leader who does not have the principles or the backbone to fight for what he was elected to do,” he said.

Turner, 40, is a longtime conservative activist who has run campaigns advocating for policies barring undocumented immigrants from renting property or attending public schools. The Torrance resident describes himself as a “self-radicalized American nationalist.”

He and Mayes once worked together as employees of San Bernardino County supervisors, Turner said, adding that at the time Mayes was more conservative.

Even if the personal attacks on Mayes are seen as retribution for siding with Democrats on cap and trade, that doesn’t mean his experience should dissuade politicians from working with members of the opposition party, said Dan Schnur, a former Republican strategist in California.

“When you enter public life, this is a risk that you accept,” Schnur said. “Voting a reliable party line on either side of the aisle doesn’t mean that you’ll be spared this type of criticism.”

Staff writer Mark Gomez contributed to this report.