In the following days, Mitchell took particular aim at Biden’s win in Georgia, tweeting that the state’s recount was a “total sham” and “A FAKE!!!” She wrote that the effort was “cover for the SOS,” referring to Secretary of State Brad Raffensperger. Responding to criticism of her appearance, she tweeted, “Happy to be considered a nut job because I believe in the rule of law.”

Mitchell largely stayed out of the spotlight in the following weeks as legions of lawyers for the Trump campaign failed in high-profile court cases across the country to get the election overturned. Behind the scenes, however, her role had escalated to the point that when President Trump on Saturday made a last-ditch phone call to get Raffensperger to “find” thousands of votes for him, it was the Washington-based Mitchell who emerged as a key player.

It wasn’t the first time Mitchell alleged election fraud.

In a case that foreshadowed her work for Trump, Mitchell worked for the campaign of Sharron Angle, who ran against Sen. Harry M. Reid of Nevada in 2010. Mitchell wrote a letter soliciting campaign contributions, alleging that “Reid intends to steal this election if he can’t win it outright….Understand, EVERYTHING we have worked for in the last year could be destroyed by dirty tricks and criminal acts.”

As evidence, she said that teachers’ union representatives were offering Starbucks cards to people who voted for Reid. The secretary of state’s office dismissed her complaint, and Reid won reelection.

Mitchell’s role as a Trump legal adviser, which received widespread attention after The Washington Post on Sunday published audio and a transcript of the call, has surprised some colleagues, particularly because she is a partner at a major law firm, Foley & Lardner, that immediately faced questions about whether it endorsed such work.

In a statement Monday, the firm said it was “aware of, and are concerned by, Ms. Mitchell’s participation in the January 2 conference call and are working to understand her involvement more thoroughly.” The firm noted that as a matter of policy, its attorneys do not represent “any parties seeking to contest the results of the presidential election,” although it did allow attorneys to observe recounts voluntarily as private citizens.

Throughout the hour-long call, Trump displayed an extraordinary degree of reliance on Mitchell. She is a onetime Democratic member of the Oklahoma legislature who became a Republican and has made a Washington career representing GOP candidates, committees and causes, culminating with her work after the election advising Trump.

At the outset of the call, Trump chief of staff Mark Meadows said Mitchell was “not the attorney of record but has been involved” in the campaign’s lawsuits seeking to overturn Biden’s Georgia victory. The attorney of record, Kurt Hilbert, declined to comment.

Stephen Gillers, an ethics expert at New York University Law School, said the issue facing Mitchell is probably one relating to the law firm policy, adding, “I’m sure the firm is dismayed by the appearance of its lawyer on the transcript.”

Mitchell declined to comment.

Mitchell, 70, began her political career as a Democrat, helping win passage of Oklahoma’s Equal Rights Amendment for women, making history in the state legislature as the first female in the nation to chair a House budget and appropriations committee.

In an oral history, she said that she authored a successful proposal to have Oklahoma become the first state to have universal preschool. “I insisted that it couldn’t be means-based,” she said. “It had to be universal…It wasn’t just some other people who were poor kids.”

Mitchell, then known by her maiden name of Deatherage, married Duane Draper, a fellow Oklahoman, and divorced in 1982. He later came out as a gay man, became director of the Massachusetts AIDS policy office and died in 1991; he had the disease when he died.

Mitchell married her second husband, Dale Mitchell, chairman of the board of Fidelity National Bank, in 1984, taking his last name. In exchange, according to a story at the time in the Oklahoman, he agreed to change his Republican registration to Democrat. Two years later, she ran unsuccessfully for lieutenant governor in the Democratic primary.

In 1992, Dale Mitchell was convicted of bank fraud, an experience that Cleta Mitchell later said was the result of “overreaching government regulation.” She became increasingly disenchanted with the social liberal policies she had supported and moved to Washington to become director of the Term Limits Institute. She advocated for allowing states to impose term limits on members of Congress, a measure that the Supreme Court ruled unconstitutional. The combination of events led her to switch her registration to independent and then Republican.

A glowing 1996 New Yorker profile of her after she arrived in Washington, headlined “The Outsider,” described her as having given up the pursuit of elected office and setting herself as a leader of “antipolitical action.” The story quoted her as saying she used to be a social liberal who would “sit in the state capitol thinking of all the good things I could do with other people’s money” but eventually turned against what she called “our entitlement mentality.”

With her background as a Democrat and her newfound fervor as a Republican, she was courted by Washington’s conservative activists, and she became a leading lawyer for GOP candidates and committees.

“She came on the scene as a principled conservative Democrat,” referring to her fiscal outlook, “and emerged as a leader” among conservatives, said Grover Norquist, president of Americans for Tax Reform, who hosts a weekly meeting in Washington for conservative activists and intellectuals.

She became associated with legal matters involving the Republican Party, the National Rifle Association and other politically active groups — particularly around campaign finance law.

“She talked to Republicans about how efforts to promote voter integrity and campaign finance reform were weaponized by Democrats as a way of limiting the political power of conservatives,” Norquist said. “She had a working knowledge of the Democratic Party and brought to Republicans an awareness of how Democrats” were advocating for politics that would effectively “shut down political opponents.”

One of Mitchell’s high-profile cases concerned a challenge to the McCain-Feingold campaign finance law brought by the National Rifle Association and others in 2002.

Mitchell was co-counsel in that case with Charles Cooper, a conservative constitutional lawyer also representing the NRA. The pair argued that the law’s ban on soft money and other activities limited the first amendment rights of the NRA and other groups. The court largely upheld the law in that case, but in subsequent challenges ruled in favor of claims that campaign finance rules undermined First Amendment rights of free speech.

“She is a very solid lawyer and very knowledgeable in election and campaign finance law,” Cooper said.

Cooper said he listened to audio of the Saturday phone in which Mitchell advocated for Trump’s effort to overturn the election. While Cooper said he does not believe “the Trump challenges to the election in Georgia or any other state have any merit whatsoever,” he said that Mitchell, in her role in the call, “was expressing a lawyerly frustration with an inability to obtain data necessary to investigate their concerns and to verify the secretary of state’s defenses.”

In the Saturday call, Trump told Raffensperger that he risked facing criminal consequences if he didn’t “find” enough votes to declare that the president had won the state. Raffensperger responded that “the challenge that you have is, the data you have is wrong.”

Trump then asked Mitchell, “Well, Cleta, how do you respond to that. Maybe you tell me?”

Mitchell complained to Raffensperger that “we have asked from your office for records that only you have” but had not received them.

Mitchell raised her claim that around 4,500 people voted after having moved out of Georgia. Trump interjected that the number was “in the 20s,” apparently meaning in the 20-thousands, but Raffensperger’s general counsel, Ryan Germany, said those numbers were not accurate. “Every one we’ve been through are people that lived in Georgia, moved to a different state, but then moved back to Georgia legitimately.”

Mitchell concluded her contribution by saying that she hadn’t even addressed the claim that voting machines were rigged, which Georgia officials denied. Trump interjected that “we don’t need” to prove that machines were rigged.

Trump said, “All we have to do, Cleta, is find 11,000-plus votes.”