Two days after the 2020 election, Virginia Thomas, the wife of Justice Clarence Thomas, texted an old friend, Mark Meadows, the chief of staff to President Donald J. Trump.

She sent messages that had been making the rounds on pro-Trump sites, where anger over the election echoed her own raw feelings, including this passage: “Biden crime family & ballot fraud co-conspirators (elected officials, bureaucrats, social media censorship mongers, fake stream media reporters, etc) are being arrested & detained for ballot fraud right now & over coming days, & will be living in barges off GITMO to face military tribunals for sedition.”

Then she added of this fanciful, if chilling, set of conspiracy theories: “I hope this is true.”

She texted Mr. Meadows again the next day. “Do not concede,” she wrote. “It takes time for the army who is gathering for his back.”

The messages were among a flurry of text traffic between Ms. Thomas and Mr. Meadows that was revealed this past week, part of a trove of documents previously turned over to the House committee investigating the Jan. 6 attack on the Capitol. (Ms. Thomas has openly opposed the committee and called for Republicans who serve on it to be expelled from the House Republican conference.)

A hard-line conservative activist, Ms. Thomas had long been viewed with suspicion by the Republican establishment. Yet her influence had risen during the Trump administration, especially after Mr. Meadows, who like Ms. Thomas has roots in the Tea Party movement, became chief of staff. Now, an examination of her texts, woven together with recent revelations of the depth of her efforts to overturn the election, shows how firmly she was embedded in the conspiratorial fringe of right-wing politics, even as that fringe was drawing ever closer to the center of Republican power.

The disclosures add urgency to questions about how Ms. Thomas may have leveraged her marriage to Justice Thomas, who would be ruling on elections cases throughout the battle over the 2020 vote and beyond. As his wife agitated for Mr. Trump and his aides to turn aside the election results, Justice Thomas was Mr. Trump’s staunchest ally on the Supreme Court and has remained so. This year, in January, he was the only justice who noted a dissent when the court allowed the release of records from the Trump White House related to the Jan. 6 attack.

Calls intensified this past week for Justice Thomas to step aside from such cases. Senator Ron Wyden, Democrat of Oregon, said on Friday that Justice Thomas “needs to recuse himself from any case related to the Jan. 6 investigation, and should Donald Trump run again, any case related to the 2024 election.”

The Thomases have been a fiercely close couple for decades. In his memoir, Justice Thomas wrote that they were “one being — an amalgam” and called her his “best friend.” She often uses similar language to describe her husband.

In one of his texts to Ms. Thomas, Mr. Meadows called the election a “fight of good versus evil” and added: “Evil always looks like the victor until the King of Kings triumphs. Do not grow weary in well doing. The fight continues.”

“Thank you!! Needed that!” Ms. Thomas replied. “This plus a conversation with my best friend just now… I will try to keep holding on. America is worth it!”

Ms. Thomas’s texts to Mr. Meadows tap into a deep well of debunked conspiracy theories. References to the rounding up of elected officials, reporters and bureaucrats for military tribunals at Guantánamo Bay are drawn from QAnon, which imagines Satan-worshipping leaders running the country and trafficking children.

Yet in the days after the election, Ms. Thomas had far more standing to take action than most who embraced such canards. As Mr. Trump courted Justice Thomas during his years in office — curious about his popularity among the Republican base and also about rumors that he might retire, aides said — the justice’s wife won increasing access to the White House.

Though some Trump aides came to view her with such suspicion that they assembled opposition research meant to damage her standing with Mr. Trump — among other things, she pressed the president to hire people who could not pass background checks, the aides said — her clout grew with time.

The arc of her political career had also led her to a powerful new platform. Ms. Thomas had started out working for establishment right-leaning organizations like the Heritage Foundation and the U.S. Chamber of Commerce. But her desire for more radical change had led her to the Tea Party, and increasingly to the party’s fringes. Mr. Meadows, who was appointed chief of staff in March 2020, held similar views and has attended meetings of Groundswell, a group that Ms. Thomas founded in 2013 after consulting with Stephen K. Bannon, who would later become Mr. Trump’s chief strategist.

With their brand of conservatism ascendant, Ms. Thomas had been appointed in 2019 to the nine-member board of CNP Action, an offshoot of a secretive but influential conservative group called the Council for National Policy, whose membership includes leaders of the National Rifle Association, the Family Research Council and the Federalist Society.

The New York Times Magazine, in a profile of the Thomases published last month, detailed CNP Action’s assertive role in efforts to overturn the presidential election. That included circulating a document to its members in November 2020 urging them to pressure Republican lawmakers in swing states to challenge the results and appoint alternate slates of electors: “Demand that they not abandon their Constitutional responsibilities during a time such as this,” the document said.

In one of her texts, the contents of which were earlier reported by The Washington Post and CBS News, Ms. Thomas sent Mr. Meadows a link to a video featuring Steve Pieczenik, a former State Department official who was claiming that mail-in ballots had been watermarked as part of an elaborate government sting operation to catch voter fraud. Mr. Pieczenik previously appeared on a webcast with the conspiracy theorist Alex Jones and claimed that the 2012 school massacre in Newtown, Conn., was a false-flag operation, a notion that has been thoroughly debunked.

On Nov. 19, Ms. Thomas promoted the efforts of Sidney Powell, the Trump lawyer who spent much of the postelection period spreading conspiracy theories. “Sidney and her team are getting inundated with evidence of fraud,” Ms. Thomas wrote to Mr. Meadows. “Make a plan. Release the Kraken and save us from the left taking America down.”

That same day, Ms. Powell held a news conference with Rudolph W. Giuliani, one of Mr. Trump’s lawyers, at the Republican National Committee headquarters in Washington. There, she laid out baseless allegations that a cabal that included Chinese software firms, international shell companies and the financier George Soros had conspired to hack America’s voting machines.

At that time, Ms. Powell was in the early stages of preparing four federal lawsuits that would present this purported plot as a reason for judges to overturn the election results. She nicknamed her suits the “Krakens,” referring to a giant octopus-like sea creature.

By Dec. 10, John Eastman, a former Supreme Court clerk for Justice Thomas and a close friend of the Thomases, went on “War Room,” a podcast hosted by Mr. Bannon.

Mr. Eastman urged the Supreme Court to intervene and said the country was in the midst of a constitutional crisis. Behind the scenes, he was advising Mr. Trump and his campaign on a proposal regarded as outlandish by many other lawyers — that Vice President Mike Pence could refuse to accept swing-state electoral votes and send them back to the state legislatures when he presided over the certification of the election in a joint session of Congress on Jan. 6. Mr. Eastman’s role would only become fully clear months later.

Around the same time, CNP Action, with Ms. Thomas on its board, circulated a report titled “Five States and the Election Irregularities and Issues,” focusing on five swing states where Mr. Trump and his allies were already pressing litigation.

The report warned that time was running out for the courts to “declare the elections null and void”; an accompanying newsletter pressed for swing states to turn back the voters’ will and name an alternate slate of electors. Cleta Mitchell, a friend of Ms. Thomas who was one of the election lawyers advising Mr. Trump, was a co-author of the report.

Ms. Thomas has not responded to requests for comment. In recently published remarks, she downplayed her role at CNP Action but also said she had attended the Jan. 6 rally at the Ellipse in Washington and “was disappointed and frustrated that there was violence that happened following a peaceful gathering.”

One of the rally organizers, Dustin Stockton, told The Times that Ms. Thomas had played a mediating role among different factions of organizers ahead of the rally. Ms. Thomas disputed that account and said she “played no role with those who were planning and leading the Jan. 6 events,” a claim undercut by her communications with Mr. Meadows, who was deeply involved in planning the protests that led up to the storming of the Capitol.

A number of her allies and associates have rallied around her in recent weeks. Two fellow members of the Council for National Policy — Edwin Meese III, who was attorney general in the Reagan administration, and J. Kenneth Blackwell, a former Ohio secretary of state — published a joint defense of the Thomases earlier this year. Recent reporting about her, they wrote, amounted to “cancel culture taken to a level that threatens our institutions of government” and was an attempt “to delegitimize a distinguished and senior member of the best-functioning branch of the federal government by smearing his wife.”

Yet in the immediate aftermath of Jan. 6, the Council for National Policy circulated in its newsletter a memo, written by one of its members, that outlined strategies to make the Capitol riot seem more palatable. “Drive the narrative that it was mostly peaceful protests,” the memo advised. “Amplify the concerns of the protesters and give them legitimacy.”

On Jan. 10, Ms. Thomas texted Mr. Meadows to express her disgust that Mr. Pence had not gone along with efforts to keep Mr. Trump in power. “We are living in what feels like the end of America,” she wrote. “Most of us are disgusted with the VP and are in listening mode to see where to fight with our teams. Those who attacked the Capitol are not representative of our great teams of patriots for DJT!! Amazing times. The end of liberty.”

In her speeches and communications with other activists, Ms. Thomas regularly invokes her husband’s name. Last summer, she invited Gov. Ron DeSantis of Florida, a Republican, to speak at a meeting of Groundswell, which she referred to as a “cone of silence coalition.” In an email to Mr. DeSantis’s staff, which was obtained through a public records request by the watchdog group American Oversight, she wrote that the justice had been in contact with the governor “on various things of late.”

“We start and end each meeting with prayer, but the Left has all the cultural institutions now and seem to be weaponizing them against conservatives and basic freedoms,” she said in her email, adding that she was hoping Mr. DeSantis could “pick us up and refocus us — as Washington is not where our hope lies.”