The wine flowed. Donald Trump Jr. mingled with the guests. And Peter Thiel, the tech billionaire and host of the event, had a message for the well-heeled crowd: It was time to clean house.

The fund-raiser at Mr. Thiel’s Miami Beach compound last month was for a conservative candidate challenging Representative Liz Cheney of Wyoming for a spot on the ballot in November’s midterm elections. Ms. Cheney, one of several Republicans who had voted to impeach President Donald J. Trump on charges of inciting the Jan. 6 storming of the U.S. Capitol, was the face of “the traitorous 10,” Mr. Thiel said, according to two people with knowledge of the event, who were not authorized to speak publicly. All of them had to be replaced, he declared, by conservatives loyal to the former president.

Mr. Thiel, who became known in 2016 as one of the biggest donors to Mr. Trump’s presidential campaign, has re-emerged as a key financier of the Make America Great Again movement. After sitting out the 2020 presidential race, the venture capitalist this year is backing 16 Senate and House candidates, many of whom have embraced the lie that Mr. Trump won the election.

To get these candidates into office, Mr. Thiel has given more than $20.4 million. That essentially puts him and Kenneth Griffin, the chief executive of the hedge fund Citadel, in a tie as the largest individual donors to Republican politics this election cycle, according to the nonpartisan research organization OpenSecrets.

What sets Mr. Thiel’s spending apart, though, is its focus on hard-right candidates who traffic in the conspiracy theories espoused by Mr. Trump and who cast themselves as rebels determined to overthrow the Republican establishment and even the broader American political order. These campaigns have raised millions in small-dollar donations, but Mr. Thiel’s wealth could accelerate the shift of views once considered fringe to the mainstream — while making himself a new power broker on the right.

“When you have a funder who is actively elevating candidates who are denying the legitimacy of elections, that is a direct assault on the foundation of democracy,” said Lee Drutman, a senior fellow at the left-leaning group New America, who studies campaign finance and hyperpartisanship.

The candidates Mr. Thiel has funded offer a window into his ideology. While the investor has been something of a cipher, he is currently driven by a worldview that the establishment and globalization have failed, that current immigration policy pillages the middle class and that the country must dismantle federal institutions.

Mr. Thiel has started articulating his thinking publicly, recently headlining at least six conservative and libertarian gatherings where he criticized the Chinese Communist Party and big tech companies and questioned climate science. He has taken issue with what he calls the “extreme dogmatism” within establishment institutions, which he said had sent the country backward.

At an October dinner at Stanford University for the Federalist Society, he spoke about the “deranged society” that “a completely deranged government” had created, according to a recording of the event obtained by The New York Times. The United States was on the verge of a momentous correction, he said.

“My somewhat apocalyptic, somewhat hopeful thought is that we are finally at a point where things are breaking,” Mr. Thiel said.

Mr. Thiel, 54, has not publicly said what he believes about the 2020 election. But in Mr. Trump, he sees a vessel to push through his ideological goals, three people close to the investor said. The two men met recently in New York and at the former president’s Mar-a-Lago club in Palm Beach, Fla. Mr. Thiel also funded an app company run by John McEntee, one of Mr. Trump’s closest aides, two people with knowledge of the deal said.

Unlike traditional Republican donors who have focused on their party’s winning control of Congress and the White House, Mr. Thiel has set his sights on reshaping the Republican agenda with his brand of anti-establishment contrarianism, said Stephen K. Bannon, Mr. Trump’s former chief strategist.

“I don’t think it’s just about flipping the Senate,” said Mr. Bannon, who has known Mr. Thiel since 2016. “I think Peter wants to change the direction of the country.”

Mr. Thiel’s giving is expected to make up just a small fraction of the hundreds of millions of dollars that are likely to flow through campaigns this cycle. But the amounts he is pouring into individual races and the early nature of his primary donations have put him on the radar of Republican hopefuls.

In the past, many courted the billionaire Koch brothers or Sheldon Adelson, the late casino magnate. This year, they have clamored for invitations to Mr. Thiel’s Los Angeles and Miami Beach homes, or debated how to at least get on the phone with him, political strategists said.

Mr. Thiel personally vets the candidates he gives to, said three Republican strategists, who declined to be named for fear of retaliation. In addition to Harriet Hageman, the challenger to Ms. Cheney, he is backing Joe Kent and Loren Culp, both of whom are running against House Republicans in Washington State who voted to impeach Mr. Trump. He also gave to a political action committee associated with Senator Ted Cruz, Republican of Texas, who is not up for re-election this year.