The president claimed without evidence on Monday that Kamala Harris had violated campaign-finance law, essentially by paying superstars for endorsements “under the guise of paying for entertainment.”

Beyoncé appeared with Vice President Kamala Harris at a rally in Houston last October. Credit…Erin Schaff/The New York Times

President Trump is calling for a “major investigation” into the celebrities Bruce Springsteen, Beyoncé, Oprah Winfrey and Bono, bringing his retribution campaign to the music industry.

Mr. Trump, in a pair of posts on Truth Social on Monday, argued that Kamala Harris as the Democratic Party nominee was violating campaign-finance law, essentially by paying those figures for endorsements “under the guise of paying for entertainment.”

There is no evidence that Ms. Harris paid for the endorsements, although details on celebrity engagements can be somewhat murky. Under campaign finance law, campaigns are required to pay the fair-market value for the costs of events so as to make sure that a company or individual is not donating in excess of federal contribution limits.

Ms. Harris paid $1 million to Ms. Winfrey’s production company for a live-streamed town hall in Detroit, according to campaign-finance records. Ms. Winfrey has said the money paid for costs and salaries related to the event and was not a personal fee.

Beyoncé headlined a rally for Ms. Harris in her hometown of Houston for an abortion-rights event, and Ms. Harris’s campaign paid the singer’s company $165,000 in November for “campaign event production,” according to campaign-finance records. Mr. Trump falsely claimed on Monday that her payment was $11 million, citing unspecified “news reports.” The artist’s mother has called that figure a “lie.”

Mr. Trump’s angry posts come as his ire has been raised against Mr. Springsteen, who sharply criticized Mr. Trump during a concert in Manchester, England, last week. Mr. Trump responded with a social media post calling him a “dried out ‘prune’ of a rocker.” Mr. Springsteen performed at a rally in Atlanta in the final weeks of the presidential race, though no records available yet show any payment from Ms. Harris’s campaign.

It was not clear why Mr. Trump named Bono, the Irish singer-songwriter who fronts the band U2. While he is a friend of former President Joseph R. Biden Jr. and received from him a Presidential Medal of Freedom, the country’s highest civilian award, he did not appear at any campaign events with Ms. Harris, nor did he endorse her.