The band sent the message Saturday night after Walker took the stage at the Iowa Freedom Summit to their song "I'm Shipping Up to Boston."
Dropkick Murphys has been vocally supportive of union rights and critical of Walker's steps to effectively end collective bargaining for public workers in Wisconsin.
In 2012, the band also asked then-Wisconsin Assembly Speaker Jeff Fitzgerald, a Republican ally of Walker's, not to play the song after he used at the state Republican Party convention.
Walker's spokesman had no immediate comment Monday.
Walker has continued to play John Mellencamp songs even after the rocker expressed displeasure.
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