More than half of Teamsters members back former President Trump in the upcoming election over Vice President Harris, according to a poll of members as the group's leadership weighs an endorsement.

The Teamsters, which is one of the largest unions in the country, said a poll of members conducted after last week's debate between Harris and Trump found 58 percent backed Trump compared to 31 percent who supported the vice president. The poll was conducted by Lake Research Partners.

“For the past year, the Teamsters Union has pledged to conduct the most inclusive, democratic, and transparent Presidential endorsement process in the history of our 121-year-old organization — and today we are delivering on that promise to our members,” Teamsters President Sean O’Brien said in a statement.

“Our members are the union, and their voices and opinions must be at the forefront of everything the Teamsters do," he continued. "Our final decision around a possible Presidential endorsement will not be made lightly, but you can be sure it will be driven directly by our diverse membership."

The latest poll showed a significant shift among membership since President Biden ended his candidacy in late July. A poll conducted from April 9 to July 3 of members found Biden had the support of 44 percent of members, compared to 36 percent who backed Trump.

The Teamster's executive board announced on Wednesday afternoon it would not endorse a candidate in this year's presidential election.

“Our mission as union representatives is clear: to be honest and upfront, to be inclusive and, above all, to be transparent with our membership," O'Brien said in a statement. "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," he added. "But this year, no candidate for President has earned the endorsement of the Teamsters’ International Union.”

Trump met with Teamsters officials in January as he courted the organization's endorsement. Harris met Monday with the group's leadership in Washington, D.C.

The Teamsters union endorsed Biden during the 2020 election, before O’Brien was elected president in 2021, and has historically endorsed Democratic presidential candidates.

But O’Brien has pushed back on the idea that the union should automatically endorse the Democrat, even before Biden dropped out of the race in mid-July amid concerns about his age and mental acuity. O'Brien spoke in prime time during the Republican National Convention. He did not address the Democratic convention.

The former president lost union members by 8 percentage points in the 2016 election, according to exit polling, and that margin grew to 14 percentage points in 2020.

Harris has earned the support of several major organized labor groups since she replaced President Biden atop the Democratic ticket, including the UAW. Harris has signaled she will carry on with much of the same labor policies as Biden, who often touted himself as the most pro-union president in history.

A Fox News poll conducted in July found Harris with a 30 percentage point lead over Trump among union voters. The poll was conducted before Biden ended his candidacy.

— Updated at 3:11 p.m.