MADISON, Wis. (AP) — Rocker John Mellencamp wants Republican Gov. Scott Walker to know he supports union rights and says Walker should think about that before using his songs on the campaign trail. It's the second time in four years Mellencamp has chided Walker for using one of his songs while running for office. Walker championed a law in 2011 that effectively ended collective bargaining for most public workers. During a recall campaign in 2012, Walker played the Mellencamp song "Small Town." When Walker launched his re-election campaign Tuesday, he played "Pink Houses." Mellencamp publicist Claire Mercuri tells The Associated Press in an email Wednesday that the rocker is not asking Walker to stop playing the song. But he wants Walker to know that he supports unions and collective bargaining.