Marine veteran Al Baldasaro defends the donations of Republican presidential candidate Donald Trump at a May 31 news conference at Trump Tower in New York, where Trump addressed issues about the money he pledged to donate to veterans groups. (Spencer Platt/Getty Images)

Donald Trump has violated federal tax law by turning his charitable foundation into “a political tool” and trumpeting its donations to veterans’ groups during his campaign events, a liberal group alleged Friday in a complaint to the IRS.

The American Democracy Legal Fund, headed by longtime Democratic operative Brad Woodhouse, formally requested that the IRS open an investigation into the Donald J. Trump Foundation. In the past, the same group has filed complaints about possible ethical or campaign violations by Republicans, and at least two complaints about Sen. Bernie Sanders (D-Vt.) and his campaign against former secretary of state Hillary Clinton.

In this case, the group’s complaint asked the IRS to consider levying new taxes on the group, which is an IRS-certified nonprofit organization.

The complaint centers on a fundraiser that Trump held for veterans’ groups in Iowa in January, which brought in more than $4 millions from other donors. Trump directed more than $2 million of this money into his foundation, which he’d established in 1987.

After that, Trump would interrupt his campaign rallies in Iowa to give away checks from the foundation, calling up local veterans’ groups to receive them onstage.  Then — several months later, and under pressure to give the rest of the donated money away — Trump held a news conference at Trump Tower, where he announced the foundation’s remaining gifts.

Federal law requires that nonprofit groups like the Trump Foundation keep their distance from presidential politics. The IRS says nonprofit organizations “are absolutely prohibited from directly or indirectly participating in, or intervening in, any political campaign.”

But this year, the line between Trump’s charity and his campaign has been blurred.  In Iowa, the oversized checks given to veterans’ groups often had the nonprofit’s name in one corner, and the campaign’s slogan on the bottom. At Trump Tower, Trump announced the gifts at a news conference dedicated mainly to his campaign, standing at a podium with the same campaign slogan: “Make America Great Again.”

“Mr. Trump, the Foundation president, deliberately thrust the Foundation into his campaign by making it a pivotal topic of discussion at numerous campaign-sponsored events and using his political limelight to focus attention on Foundation activities,” Woodhouse wrote in a letter to the IRS. “The Foundation has inserted itself into an inherently political presidential campaign in direct violation of” the law, he wrote.

Neither the IRS nor the Trump campaign responded immediately to questions from The Washington Post on Friday afternoon.

Previously, legal experts have said that an IRS investigation of the Trump Foundation — if the agency did actually investigate — might not be complete for many months or years. In theory, violations of this rule might result in tax penalties, or even the loss of a charity’s nonprofit status. But in practice, such outcomes are rare, legal experts said.