The International Brotherhood of Teamsters declined to endorse a presidential candidate on Wednesday after releasing internal polling that showed a majority of its members supported former President Donald Trump over Vice President Kamala Harris.

It’s the first time in nearly three decades that the union has not endorsed a presidential candidate.

“Unfortunately, neither major candidate was able to make serious commitments to our union to ensure the interests of working people are always put before Big Business,” Teamsters President Sean O’Brien said in a statement. “We sought commitments from both Trump and Harris not to interfere in critical union campaigns or core Teamsters industries – and to honor our members’ right to strike – but were unable to secure those pledges.”

Ahead of the decision, the Teamsters shared internal data showing that a majority of members supported Trump over Harris. According to an electronic member poll that was initiated after President Joe Biden withdrew from the race, about 60% of members believed the union should endorse Trump while 34% supported Harris. About 6% said they supported another candidate.

“It’s a great honor. They’re not going to endorse the Democrats. That’s a big thing,” Trump said during a campaign stop in New York City on Wednesday. “Democrats automatically have the Teamsters. They took a vote, and I guess I was at 60% or more, and that’s a great honor.”

Harris met with Teamsters leaders on Monday. O’Brien had a prime-time speaking slot at this summer’s Republican National Convention but did not appear at the Democratic convention the following month.

The Teamsters, which represents truck drivers, freight workers and other workers, is the last major labor union to announce a presidential endorsement. The nation’s other major labor organizations, including the American Federation of Teachers and the United Auto Workers, have backed Harris.

The last time the Teamsters sat out a presidential election was 1996. It endorsed Democratic nominees in the ensuing six elections, including Trump’s opponents Hillary Clinton in 2016 and Biden in 2020. The union last backed a Republican presidential candidate in 1988, with an endorsement of George H.W. Bush.

CNN previously reported that rank-and-file union membership had large pockets of Trump support, even as major labor leaders endorsed Harris.

Before Biden dropped out of the race, Teamsters officials had suggested to various stakeholders that the union could remain politically neutral this cycle for the first time in decades.

“At the end of the day, the Teamsters are not interested if you have a “D,” “R” or an “I” next to your name. We want to know one thing,” O’Brien said at the RNC. “What are you doing to help American workers?”

An endorsement from the Teamsters, which counts members across a variety of industries and is heavily represented in critical swing states such as Michigan, Wisconsin and Pennsylvania – all of which went for Trump in 2016 before backing Biden four years later – would have been a crucial get for either candidate.

The Teamsters internal data also revealed that a town hall straw poll taken before Biden exited the race showed him with 44% of members’ support compared with Trump’s 36%. That survey also included Robert F. Kennedy Jr., who garnered about 6% of members’ support. Kennedy has since suspended his campaign and endorsed Trump.

Meanwhile, the president of the Teamsters’ National Black Caucus questioned the union’s decision to withhold an endorsement in the 2024 presidential race and suggested O’Brien was afraid to have “hard conversations” with members.

“I’m not going to harp on the disappointment that my national leadership did not have the courage or the fortitude to stand up to this bully and to be able to go out and tell our entire membership, this is the best thing for you as members,” James “Curb” Curbeam, a member of Teamsters Local 480 in Nashville, said in reference to Trump.

He also called into question the polling methodology used to support the union’s decision.

“What is the actual number of people that took part in the polls?” Curbeam asked.

Curbeam said the Black Caucus would do its own organizing in support of Harris.

The Teamsters’ endorsements of Clinton and Biden in the past two presidential cycles came under previous leadership. While union members are thought of as a traditionally Democratic voting bloc, Trump has been working to make inroads among rank-and-file members.

Biden had long enjoyed strong union support. He became the first sitting president to visit a picket line last September and frequently employed some version of the line, “The middle class built America, and unions built the middle class” in many of his stump speeches during his time as candidate. Harris has also begun using that line.

But Harris does not have the same long history with unions and working people as the president.

Her running mate, Minnesota Gov. Tim Walz, is himself a former union member as a public school teacher.

This story has been updated with additional information.

CNN’s Eva McKend, Aaron Pellish and Kate Sullivan contributed to this report.