International Brotherhood of Teamsters President Sean O’Brien plans to address the Republican National Convention in Milwaukee next month, in what would be a rare appearance by a high-profile labor leader at the GOP’s quadrennial meeting.

Former President Donald Trump announced the news on his social media platform Truth Social on Friday, saying O’Brien had “accepted my invitation.”

“Sean, I look forward to seeing you represent the Teamsters in Milwaukee,” Trump said. “Together we can Make America Great Again.”

A Teamsters spokesperson confirmed the planned appearance in an email and said O’Brien had asked to speak at both the Democratic and GOP conventions.

“This is truly unprecedented since it will be the very first time a Teamsters General President has addressed the RNC,” the spokesperson said. “Our 1.3 million members represent every political background, and their message needs to be heard by as wide an audience as possible, and that includes all political candidates running for elected office.”

Most major unions have either publicly opposed or kept their distance from Trump, whose agenda as president was extremely hostile to organized labor. The Teamsters endorsed President Joe Biden during his 2020 run against Trump, but so far, the union has declined to throw its backing behind either candidate for 2024.

In the meantime, O’Brien appears happy to hear Trump out. He and other top Teamsters met with the former president in January, rankling members who strongly oppose a Trump return to the White House.

O’Brien, who took the helm of the union in March of 2022, said it was important to speak with all candidates.

“There’s always a threat to organized labor, so we want to be proactive and make certain every candidate — not just President Biden — understands how important our issues are,” he told Politico in March.

When Trump was president, he wasn’t exactly friendly to organized labor. He installed members on the National Labor Relations Board who made it more difficult for workers to organize unions and rolled back several workplace regulations meant to improve safety and raise wages.

Once Biden arrived at the White House, he set to peeling back several of those Trump-era changes and shaped the NLRB into arguably its most pro-union form in decades. He also signed a coronavirus relief package that provided $86 billion in funding for troubled union pension funds, with the largest beneficiary being a Teamsters plan.

The AFL-CIO labor federation, which includes 60 unions but not the Teamsters, has already endorsed Biden for reelection. So has the United Auto Workers union, whose president, Shawn Fain, declared during the announcement in January that Trump is a “scab.”