The scathing rebuke, posted on the band's Facebook page, reads as follows:

We just got word that Wisconsin State Rep and Speaker of the State Assembly Jeff Fitzgerald used "Shipping Up To Boston" as his walk-on song yesterday at the Wisconsin GOP Convention in Green Bay.

The stupidity and irony of this is laughable. A Wisconsin Republican U.S. Senate candidate - and crony of anti-Union Governor Scott Walker - using a Dropkick Murphys song as an intro is like a white supremacist coming out to gangsta rap!

Fitzgerald: if you and your staff can't even figure out your music you might wanna give up on the politics!!!!!

We stand beside our Union and Labor brothers and sisters and their families in Wisconsin and all over the U.S!

In an even deeper irony, the song in question is based on lyrics penned by legendary folk singer and outspoken trade unionist Woody Guthrie.