Union leaders at the Irvin Works in West Mifflin say 95% of their members are in favor of the Nippon merger, and many of them were at the Trump rally in Pittsburgh one day before the election.

The union leaders say they were initially skeptical of the deal, but support grew after they met with Nippon executives who visited the area during the summer. Nippon pledged to spend $1 billion to upgrade the 86-year-old hot strip mill at Irvin.

https://www.wtae.com/article/us-steel-nippon-trump-steelworkers/63085379

Says the steelworkers union organization officially opposes it, so sounds like the union leadership is split but the workers support it.