Embattled Wisconsin Governor Scott Walker, who is fighting for his political life in a recall election forced by opponents of his anti-labor agenda, began his reelection campaign with a six-city campaign swing on Tuesday. At each event, Walker entered his gathering to the sound of John Mellencamp’s song, "Small Town."

There’s only one problem with Walker’s musical selection.

Mellencamp is pro-union.

He may be one of the country’s best-known musicians. But Mellencamp still lives in his native Indiana and continues to write songs about struggling family farmers, displaced workers and the struggles to make their voices heard.

The musician’s publicist contacted the Walker campaign to inform them of that fact Wednesday.

"He’s very pro-collective bargaining and the fight for a living wage," explained Bob Merlis.

Mellencamp is not demanding that Walker—whose attack on the collective-bargaining rights caused mass demonstrations last year and inspired the recall drive—stop using his music. But, as the rocker did when Republican John McCain started using his song "Our Country" in 2008, Mellencamp is reminding Republicans that he is not one of them—and that his songs are not written to celebrate their policies.

Five years ago, McCain got the message and stopped playing the Mellencamp song. So far, the Walker campaign has not responded to the communication from the rocker’s publicist.

But Merlis says Walker and his aides should be under no illusions about Mellencamp.

"He’s a very liberal person," Merlis says of the singer, who performed "Small Town" at a rally for Barack Obama in 2008, recorded a radio ad for Obama and appeared at Obama’s inagural in 2009.

Mellencamp has even addressed recall politics. After California Governor Gray Davis was recalled in 2003, Mellencamp referenced that election in an "Open Letter to America" that appeared on his website.

An ardent critic of former President George Bush’s Iraq War policies, Mellencamp wrote: "The Governor of California was removed from office based on finance troubles. And yet George W. Bush has lied to us, failed to keep our own borders secure, entered a war under false pretense, endangered lives, and created financial chaos. How is it that he hasn’t been recalled? Perhaps this time we could even have a real election… but that wouldn’t fit the Bush administration’s ‘take what you want and fire people later’ policy. Take an election; take an oil field; take advantage of your own people—a game of political Three-Card Monte."

Mellencamp’s dust-up with Walker has created speculation in Wisconsin that the singer might appear in the state before the June 5 election.

Democrats will choose a challenger to Walker on May 8. All four serious Democratic contenders—Milwaukee Mayor Tom Barrett, Secretary of State Doug La Follette, state Senator Kathleen Vinehout and former Dane County Executive Kathleen Falk—have endorsed the restoration of collective bargaining rights for public employees.

The campaign between the eventual Democratic nominee in Wisconsin and Republican Walker promises to be an epic battle between supporters of labor rights and those who would deny workers the right to organize.

Mellencamp, an midwesterner who has always been popular in Wisconsin, would surely be welcomed on the campaign trail by the Democratic candidate.

So who knows? Wisconsinites might yet get a chance to hear the song "Small Town" performed live.

But one thing is certain: That won’t happen at a Scott Walker rally.