Their ‘General Executive Board’ can vote all they want for Hilary but a substantial part of the rank and file members will go to Trump.
The Teamsters are not as numerous as they once were. Independents have grown as much as the Teamsters have declined.
Just like the UAW is now a bunch of medical and government employees, I assume most “Teamsters” today couldn’t drive a truck if their life depended on it.
The reason there are fewer teamsters union members is that their leadership backs democrats like Clinton.