President truman sought to support the power of unionized labor when he vetoed what bill?

Taft-Hartley Act

Explanation:

The Taft-Hartley Act was an act that guaranteed employees the right not to join unions and permitted union shops only where state law allowed them and where the majority of the workers voted for them. The Act was vetoed by President Truman. He explained his veto saying that he sympathized with workers and supported the unions but he believed the act abused the right of workers to unite and bargain with employers for fair wages and working conditions.

Because of that, he sought the support of unionized labor so his veto could not be overridden. This eventually happened on June 23rd of 1947.

i believe 5 is correct answer