The Detroit News reported earlier this week that several people wearing Auto Workers for Trump T-shirts at a Donald Trump campaign event in Michigan were not actually auto workers .

The report didnt seem to surprise Shawn Fain, president of the United Auto Workers union.

Its pathetic. Everything he does is a con, Fain said Thursday, referencing Trump.

The UAW, which is based in the crucial swing state of Michigan, has endorsed Harris, and its leader Fain has become one of Trumps most fiery critics. Fain was speaking on a call hosted by the Kamala Harris campaign ahead of Trumps scheduled address to the Detroit Economic Club.

There is a stark contrast between Donald Trump and Kamala Harris, he said. Kamala Harris has stood with labor. Shes walked the walk. Donald Trump serves himself. Hes always served himself.

Most major unions have lined up behind Harris and plan to help the Democratic nominees get-out-the-vote efforts ahead of Election Day. However, the International Brotherhood of Teamsters announced last month that it would not make an endorsement, citing membership polls showing more support for Trump among its rank and file.

Like the Teamsters, the UAW makes its endorsement (or non-endorsement) through a vote by its executive board, rather than a vote by its membership.

Asked about the Teamsters decision to stay out of the race, Fain said he believed he had a responsibility as a leader to take a stand against Trump, noting the former presidents patently anti-union record while in office. He didnt deny a significant share of the unions members would support Trump.

Quoting legendary UAW leader Walter Reuther, Fain said there was a correlation between the ballot box and the bread box, and argued that gains unions and workers have made could be lost if Trump wins the presidency.

What we bargain at the bargaining table can be taken away, he said, noting that anti-union officials appointed by Trump made it more difficult for workers to organize.