(AP Photos)

Gov. Scott Walker may think twice about playing John Mellencamp's music on the trail again, the AP reports:

Liberal rocker John Mellencamp wants Republican Wisconsin Gov. Scott Walker to know he supports collective bargaining and union rights and says Walker should be aware of that before using his song "Small Town" on the campaign trail.

Mellencamp's publicist Bob Merlis told The Associated Press on Wednesday that he sent Walker's campaign an email not asking him to stop using the song, but to inform him of Mellencamp's beliefs.

"He's a very liberal person," Merlis said of the singer. "He appeared at the Democratic National Convention in 2004. His wife at the time was a delegate at large. He's very pro-collective bargaining and the fight for a living wage."