Messina, according to Baucus, was responsible for the controversial message.

“Jim is tough,” Baucus says. “I’ll never forget when he showed me that ad. We were in Bozeman in a motel. The curtains were drawn. He said, ‘Max, what do you think?’ They were afraid I wasn’t going to like it. I loved it!”

The revelation has been seized on by the campaign’s critics on the left.

Writing in Salon, David Sirota called the spot “one of the most homophobic ads in American history.”