Actually, the Teamsters Union announced yesterday that it will not endorse Donald Trump or Kamala Harris. It won't endorse anyone. This is the first time the union has sat out a presidential election since 1996. Internal polling released yesterday shows that most members will vote for Trump, but the union leaders decided against making an endorsement, despite the UAW, AFT, SEIU, and many other unions endorsing Harris.
The nominal reason for not making an endorsement of Trump is that the leaders sought a guarantee that Trump would not interfere with internal union campaigns or core Teamsters industries and would honor their right to strike. He refused to make any of these concessions. More likely, the real reason is that the members are voting based on cultural issues like abortion and gay rights but the leadership knows very well that on economic issues, Harris would be better for the union and its members. They just think that would be a hard sell to the membership, so they declined to take a stand. Also, Harris does not have much of a history of working with unions.
In the recent past, the Teamsters have endorsed Democrats, including Joe Biden in 2020 and Hillary Clinton in 2016. The last Republican they endorsed was George H.W. Bush in 1988. (V)