The International Brotherhood of Teamsters will refrain from publicly supporting any candidate in the presidential election this year, even though the union’s members overwhelmingly prefer President Trump to Vice President Harris. 

“After reviewing six months of nationwide member polling and wrapping up nearly a year of rank-and-file roundtable interviews with all major candidates for the presidency, the union was left with few commitments on top Teamsters issues from either former President Donald Trump or Vice President Kamala Harris — and found no definitive support among members for either party’s nominee,” the general executive board for the Teamsters wrote in a statement issued on Wednesday. 

However, the member polling released by the Teamsters on Wednesday showed that nearly 60 percent of voting members supported a Trump presidency — nearly double the 34 percent that said they supported Ms. Harris. 

The latest survey results mark a stark shift in member preferences after Ms. Harris replaced President Biden as the Democratic nominee. When polled earlier this year, before Mr. Biden had dropped out of the race, 44.3 percent of union members expressed their support for the Democratic nominee while only 36.3 percent endorsed Trump. 

And yet, the union’s executive board claimed that the polling showed “no majority support for Vice President Harris and no universal support among the membership for President Trump.” 

“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,” explained the Teamsters general president, Sean O’Brien. 

He continued: “As the strongest and most democratic labor union in America, it was vital for our members to drive this endorsement process. Democrats, Republicans, and Independents proudly call our union home, and we have a duty to represent and respect every one of them. We strongly encourage all our members to vote in the upcoming election, and to remain engaged in the political process. But this year, no candidate for President has earned the endorsement of the Teamsters’ International Union.” 

The union, which represents more than 1.3 million members, endorsed Mr. Biden in the 2020 election and has supported the Democratic candidate during every election cycle dating back to Al Gore’s run in 2000. The latest decision will break the Teamster’s decades-long streak of endorsing the Democratic nominee.

The last time that the Teamsters opted out of endorsing a candidate was in 1996 when President Clinton ran against Senate Majority leader Bob Dole. Since 1960, the union has only refrained from supporting a candidate twice. 

The decision comes at a blow to both Ms. Harris and Trump, who invited Mr. O’Brien to speak at the first night of the Republican National Convention. While the Democratic National Convention hosted leaders of other unions, the Teamsters were not in attendance. Just days before the announcement, Ms. Harris reportedly hosted meetings with union members and leaders. 

The union, which represents truck drivers, firefighters, construction laborers, warehouse employees, among many other professions, boasts a significant presence in key swing states Wisconsin, Michigan, and Pennsylvania.