House Republicans are investigating reports that American Federation of Teachers union dues were used to help produce, promote, and publish union President Randi Weingarten's book, which her publisher called "a manifesto for our time."

Rep. Tim Walberg, R-Mich., chair of the House Committee on Education and the Workforce, and Rep. Rick Allen, R-Ga., chair of the Subcommittee on Health, Employment, Labor, and Pensions, wrote a letter Tuesday to Weingarten.

They cited reports that the "AFT expended substantial funds on consultants, legal services, publication-related expenses, fact-checking services, photography, and other activities connected" to her book, "Why Fascists Fear Teachers: Public Education and the Future of Democracy," which was released in September.

The New York Post reported in May that a Freedom Foundation study found that Weingarten's team used more than $1.4 million in union funds and that Weingarten retained a share of the proceeds.

The report stated that Weingarten's team included an attorney who reportedly worked on the book pro bono but whose firm raked in $977,000 for various work for the teachers union, as well as a "ghost writer" who earned more than $400,000 from the union.

"The prospect that rank-and-file educators' dues may have financed a project that generated private financial gain raises serious questions about transparency, accountability, and fiduciary responsibility within one of the nation's largest labor organizations," the lawmakers wrote.

"These allegations, if accurate, raise significant questions regarding transparency, fiduciary obligations to union members, and the use of member dues."

Weingarten publicly stated that some of the proceeds from the book would go back to the AFT, the AFT Disaster Relief Fund, and the AFT Educational Foundation, according to the Post.

The AFT's federal labor disclosures showed two "royalty payments" totaling $125,000 were made to a Weingarten-controlled entity called "Teachers Want What Kids Need, LLC," which the Freedom Foundation said was not a tax-exempt charity but "an opaque corporate entity incorporated in Delaware."

The lawmakers noted that Weingarten said the book project was undertaken in partnership with the AFT and maintained she did nothing wrong, but that "the available information warrants further review to determine the extent to which union resources were devoted to a project from which you may have personally benefited financially."

As part of the investigation, the lawmakers requested that Weingarten turn over by July 21 records of all AFT expenditures related to drafting, publishing, promoting, and touring the book. They also requested all agreements between AFT and outside parties, along with records of work performed by AFT employees on the project.

"The Committee expects your full cooperation," the lawmakers wrote.

Weingarten's annual salary with the AFT is $469,442, according to the labor watchdog Union Facts. The union has 1.8 million members across 3,000 local affiliates.

In her book, Weingarten referred to President Donald Trump as a fascist, causing a stir. She also mentioned Adolf Hitler and Benito Mussolini.

"Democracy is people power," Weingarten wrote, according to an excerpt published by Rolling Stone magazine. "But fascists want one leader or a small group of elites to have all the power. And that is what's happening in the United States right now — with billionaire Trump having enabled his shadow governing partner Elon Musk, the wealthiest person in the world, to act as his co-president."

In another excerpt, according to the Post, Weingarten wrote: "Those hell-bent on unraveling democracy, pluralism, and opportunity have always attacked teachers and education. It's a very old playbook. In the 1930s, Hitler and Mussolini persecuted teachers and tried to control the curriculum."

Newsmax has contacted the AFT for comment.