Editor's note: The story has been updated to reflect the number of times in recent election cycles that the union has not endorsed a candidate. The International Brotherhood of Teamsters will not issue an endorsement in the presidential election for the first time since 1996, and for only the third time since 1960. Teamsters General President Sean O’Brien said, “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.” “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,” O’Brien said. The Teamsters endorsed President Biden during the 2020 election, and has consistently supported Democratic presidential nominees in recent election cycle. The union notably waited to announce its endorsement decision far longer than other unions and labor organizations, including the United Auto Workers, National Education Association, Service Employees International Union and AFL-CIO, which all endorsed Biden, then Vice President Harris, after the president dropped out of the race in July. The Teamsters has endorsed GOP presidential candidates, including Richard Nixon, Ronald Reagan and George H.W. Bush, and O’Brien’s flirtation with former President Trump and Republicans sparked speculation the union could once again break from the pack. O'Brien has worked to build inroads with Republicans such as Sen. Josh Hawley (R-Mo.) as the union works to advance policy priorities including the Protecting Workers Right to Organize (PRO) Act, which would strengthen workers' ability to form a union and bargain, and opposition to the national right to work. The union's PAC also made its first contribution to the Republican National Committee this cycle since 2006, donating $45,000 to the committee's convention fund about a week before Trump spoke at a Teamsters roundtable in late January, according to Federal Election Commission data. The union also hosted roundtable discussions with Harris, Biden and third-party candidates Robert F. Kennedy Jr. and Cornel West as part of the endorsement process. Harris has supported the PRO Act on the campaign trail, and O’Brien told reporters Monday that there wasn’t a “whole lot of difference” between Harris’s roundtable and Biden’s, who the union leader said “has been great for unions.” Some Teamsters locals and caucus members, including the National Black Caucus of the International Brotherhood of Teamsters, have also endorsed Harris. But O'Brien also said his members' input would be a "significant" part of the endorsement process, and recent polling shows members clearly support Trump in the presidential race. While 44.3 percent of union members polled between April 9 and July 3 backed Biden compared to 36.3 percent for Trump, polling in the wake of the Republican and Democratic Party conventions found the Teamsters members support Trump over Harris. In a union-commissioned survey conducted by an independent third party between July 24 and Sept. 15, 59.6 percent of Teamsters members voted to endorse Trump, compared to 34 percent for Harris. In a separate Teamsters-commissioned poll during the week ending Sept. 15, 58 percent of Teamsters members voted to endorse Trump, compared to 31 percent who voted to endorse Harris. The lack of an endorsement is a big blow to Trump, who invited O’Brien to be the first Teamsters leader in the union’s 121-year history to speak at the Republican National Convention in July. The move prompted backlash from labor leaders and antiunion activists alike but gave him a platform to take on corporate bosses, antiunion elites and the status quo in Washington. “The Teamsters are doing something correct if the extremes in both parties think I shouldn’t be on this stage,” O’Brien said. “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: What are you doing to help American workers?” O’Brien rebuked Trump weeks later, however, after the former president floated firing striking workers during an interview with Elon Musk. “I mean, I look at what you do,” Trump told Musk. “You walk in, you say, ‘You want to quit?’ They go on strike, I won’t mention the name of the company, but they go on strike, and you say, ‘That’s OK, you’re all gone. You’re all gone. So, every one of you is gone.’” O’Brien called such a proposal “economic terrorism.” Trump's campaign highlighted the results of internal polls later Wednesday. "While the Teamsters Executive Board is making no formal endorsement, the hardworking members of the Teamsters have been loud and clear— they want President Trump back in the White House! These hardworking men and women are the backbone of America and President Trump will strongly stand up for them when he’s back in the White House," Trump national press secretary Karoline Leavitt said. The Republican Party has struggled to court union leadership broadly, and Americans are less likely to say the GOP best serves the interests of union members, according to a recent Gallup poll. According to the Gallup poll, 62 percent of surveyed Americans think the Democratic Party best serves labor union members, compared to 27 percent who said the same thing about the Republican Party. “The labor union voting bloc is particularly important in Pennsylvania, Nevada and Michigan, swing states where the shares of union members are higher than the national average,” Gallup noted in its analysis. But union members' concerns in an election extend beyond labor issues, and large swaths of union members and Teamsters may still vote for Trump. Exit polls from the 2020 race found about 40 percent of voters in union households voted for Trump compared to 56 percent who voted for Biden. Harris had a 10-point lead over Trump among union households in a Fox News survey released last month. While O’Brien said that “no candidate for President has earned the endorsement of the Teamsters’ International Union,” he noted the union “strongly encourage[s] all our members to vote in the upcoming election, and to remain engaged in the political process.” “Democrats, Republicans, and Independents proudly call our union home, and we have a duty to represent and respect every one of them,” O’Brien said. Updated at 4:15 p.m.