Unions went for Biden 56/40 in 2020 https://www.cnn.com/election/2020/exit-polls/president/national-results
Unions went for Harris 55/43 in 2024 https://www.politico.com/news/2024/11/06/harris-democrats-union-harris-votes-00187943
Dems lost ground and Trump picked up a not a small amount. They are voting against their self interests.
Seemed to work this year