I checked. If the publisher has been paid the usual fee for a public performance then the Bachmann campaign
does have a legal right to use the Tom Petty song. Mr. Petty can object on the basis that he doesn't subscribe to Bachmann's politics (and hope she respects his wishes) but he apparently has no
legal right to stop her from using his song, assumming the publisher has been paid a performance fee. So, I stand corrected. I also learned something about music copyright law.
I think 'CaspersGhost' (in post #31) has a point: conservative politicians should stay with American country music and not have to put up with some ancient, drug-addled rocker whining about them using it.