At a conference this month put on by Turning Point Action, a rising conservative activist group, 8,000 people packed into a Detroit convention hall to hear directly from Republicans’ presumptive nominee for president, Donald J. Trump.

But first, there was a word from a sponsor: Alexander Spellane.

Mr. Spellane, who federal regulators say is also known as Alexander Fisher and Alexander Overlie, sells investments in precious metals. Cash, stocks and 401(k)s could plummet in value, he warned from the stage, but he told the throng of Trump supporters that they could protect their money by buying gold and silver from his company, Fisher Capital.

The Commodity Futures Trading Commission has been trying to shut down Fisher Capital’s sales for the past 14 months, alleging in a lawsuit that it sold gold and silver coins at such exorbitant, deceptive prices that virtually every customer had suffered “immediate and dramatic losses on their investment.” Fisher Capital has denied the allegations.

That lawsuit did not keep Turning Point Action from embracing Fisher Capital as a top-level sponsor of the Detroit event, which has required a donation of at least $250,000 and allowed Mr. Spellane to be photographed backstage with Mr. Trump. Mr. Spellane also claims to be the largest corporate sponsor of a sister group, Turning Point USA.

Mr. Spellane’s place on the Detroit stage offers a window into how Charlie Kirk, a young conservative activist and media personality who is close to both Mr. Trump and his son Donald Jr., has blended commerce and politics to transform a fringe initiative into a juggernaut with sweeping influence in right-wing circles. Turning Point Action, an advocacy group, and Turning Point USA, a charitable organization, were each created by Mr. Kirk and have each helped rally conservatives behind Mr. Trump.

This year, Turning Point Action says it plans to spend over $100 million to turn out voters in three battleground states.

The groups’ highly polished, multimillion-dollar events, which have drawn thousands to convention halls in Phoenix, West Palm Beach and elsewhere, are underwritten by corporate sponsors, who gain access to potential customers.

While some political groups try to steer clear of corporate sponsors that might prompt blowback from politicians or other donors, the Fisher Capital example shows that Turning Point leaders are willing to look the other way to reel in cash, said Michael Steele, a former chairman of the Republican National Committee. He described Turning Point’s attitude as “as long as the check clears, I’m good.”

“It is an incestuous relationship between the folks with the money and the folks who want the money,” said Mr. Steele, a frequent Trump critic.

Andrew Kolvet, a Turning Point spokesman, said the opposite was true. “There is no lack of scrutiny to ensure we’re always abiding by relevant regulations and laws,” he said. Turning Point leaders learned of the fraud claims against Fisher Capital more than a year ago, he said, and “felt satisfied with their explanation at the time.”

“We live in a country where you are presumed innocent, and we extend that presumption to sponsors and their teams as well,” he said.

Another group that has sponsored Turning Point events is New Federal State of China, a organization that says it is dedicated to overthrowing the Chinese Communist Party. The organization has helped finance two recent annual conferences, including one in December, 10 months after prosecutors charged the group’s founder, Guo Wengui, with defrauding thousands of investors of more than $1 billion with bogus cryptocurrency deals and other schemes.

Mr. Guo has said he is innocent. Mr. Kolvet said Turning Point had no agreement with the New Federal State of China to sponsor future events.

Mr. Trump himself has been found to engage in deceptive business practices. He was convicted late last month on felony charges of falsifying business records. Last year, in a civil case in New York, he was found liable for conspiring to manipulate his net worth.

Mr. Spellane and Fisher Capital have asked a judge to dismiss the federal complaint, arguing that the regulatory agency has no jurisdiction to sue and no evidence of fraud. The firm disclosed its fees to customers and operated “in a similar vein as any retailer in this country,” according to its motion to dismiss. Mr. Spellane did not respond to questions for this article.

Turning Point has only strengthened its relationship with Mr. Spellane since the federal complaint was filed in April 2023. The Detroit conference was the third event the firm has helped finance since then, including an annual conference in December in Phoenix, which drew an estimated 13,000 people.

Mr. Spellane pledged $1 million to Turning Point USA at a February gathering at Mar-a-Lago, Mr. Trump’s Florida resort, and later announced that the group had appointed him to its advisory board.

In Detroit, Mr. Spellane played up his Turning Point ties, saying, “That’s why we are here for the third year in a row.” He ended with: “Give it up for Donald Trump, everybody!”

Listening with interest was Jeff Strasser, 57, a former carpenter and truck driver who had traveled more than two hours from Northern Michigan to hear Mr. Trump. Mr. Strasser said he was intrigued by Mr. Spellane’s statement that anyone who stopped by the Fisher Capital booth in the adjoining hall would be eligible for up to $10,000 in free silver.

He came away from the booth thinking a precious metal investment was a slam dunk. “You kind of have to be a fool not to want to do it,” he said, adding “I’m talking about maybe switching my whole 401(k) over to it.”

Ian Sangster, a Fisher account executive, said about 50 people stopped by over the weekend, some of whom signed up for a follow-up sales pitch.

Asked if Mr. Spellane’s backstage photos with Mr. Trump would be a selling point for Fisher Capital, Mr. Sangster said: “Yeah. It’s pretty cool, right?”

Both Fisher Capital and New Federal State of China have ties to high-profile Trump allies. Fisher Capital’s spokesman is Roger Stone, a Trump associate who was convicted in 2019 of lying to Congress and witness tampering. He was later pardoned by Mr. Trump.

Mr. Guo founded the New Federal State of China with Stephen K. Bannon, a former Trump strategist and keynote speaker at many Turning Point events. Neither the group nor Mr. Bannon was charged in Mr. Guo’s fraud case. Mr. Bannon was named as a co-conspirator.

Mr. Bannon was charged in a separate criminal case with swindling donors in a supposed effort to finance a wall on the Mexico border. He pleaded not guilty and was pardoned by Mr. Trump before his trial. He now faces state charges in New York stemming from the same effort. He was convicted of contempt of Congress after refusing to testify about efforts to overturn the 2020 election results and is scheduled to begin serving a four-month prison sentence next week.

Mr. Spellane is a relative newcomer to the Trump political world. Just 31, he never registered with the Commodity Futures Trading Commission to trade precious metals, as required, the agency says. Its complaint, filed less than three years after Fisher Capital opened in 2020, said the operation was meant to trick older, unsophisticated investors into swapping their retirement savings for gold and silver coins priced as high as 200 percent over their market value. The company is not connected to Fisher Investments, a Texas-based firm.

Targeting Christian conservatives was central to the scheme, according to the complaint. Salespeople falsely claimed that Fisher had teamed up with conservative media personalities — who were not named — to protect customers from a looming retirement crisis, it said.

James A. Simpson Jr., an evangelical pastor from western Ohio who visited Fisher Capital’s booth at the conference, said that the Turning Point imprimatur “absolutely” bestowed credibility on the company.

After learning of the fraud claims, Mr. Simpson, 61, said he would have hoped that Mr. Kirk, Turning Point’s founder, “would have diligently done some research as far as whether he felt the allegations were valid or not” before giving Mr. Spellane an opportunity to drum up customers. He said he would be very cautious about pursuing any investment.

Regulators are seeking to permanently bar Mr. Spellane and Fisher Capital from trading commodities like precious metals and to recoup money investors lost. Steven Adamske, a spokesman for the Commodity Futures Trading Commission, said the agency’s lawsuit was moving slowly, like most such cases.

Typically, by the time government lawyers are able to shut down an operation, “the money is already gone,” he said.

Michael Forsythe contributed reporting. Kitty Bennett and Susan C. Beachy contributed research.