ROYAL OAK, Mich. – In the hours before addressing several hundred Tea Party activists in Milford, Mich. last Thursday, Mitt Romney had another important meeting with a much smaller audience.

In a suburban Michigan home, and in the company of senior aides, Romney spoke for an hour with Bob Ritchie, a Michigander of humble roots and a checkered past, who had risen to prominence in the entertainment industry. According to a Romney aide, the two men spoke for an hour – about Michigan, bringing back Detroit, and about U.S. troops overseas.

“The other day I got in my car and I drove out to a home of a fellow that lives in this area, and I asked him whether he might come here tonight,” Romney told the crowd at a rally here tonight. “I think you know him pretty well. He’s a native son of Detroit, loves Michigan, loves Detroit."

And tonight that meeting paid dividends for Romney. Ritchie, better known as Kid Rock – an often-R-rated musician known his off-stage antics and brushes with the law as much as his musical successes – performed a rousing rendition of his hit song "Born Free" at the conclusion of Romney's final rally before the polls open here in Michigan.

Rebecca Cook / Reuters

Republican presidential candidate Mitt Romney shakes hands with musician Kid Rock at a campaign stop for Romney's supporters on Feb. 27 in Royal Oak, Mich.

The two struck an odd image together on stage, with Romney in a blazer and button-down shirt, and Kid Rock scruffy in his trademark hat, battered jeans and a leather jacket over a white t-shirt. The two men shared handshakes before and after the performance, and Kid Rock planted a hesitant kiss on Ann Romney's cheek.

But somehow, it all worked, and the single-song concert roused more than a thousand Michiganders to their feet for Kid Rock (and for Romney), just hours before votes are cast in what has become a pivotal primary state.

"Mitt, if you’re elected president, will you help me help the state of Michigan?” Romney said the rock star asked him at their meeting. "I said I would. He said, ‘If you’re elected president, will you help me help the city of Detroit?’ I said I would.

"Then I turned to him, and I said, ‘By the way, given the fact that I’m willing to do those things, will you come here and perform a concert tonight for my friends, and he said he would," Romney continued.

A Romney aide told reporters Kid Rock e-mailed Romney personally the day after their meeting to confirm he would perform at today's event. Since then, the identity of the final rally's "Mystery Musical Guest" had been a closely-guarded secret, with campaign staffers sworn to secrecy. Even the marquee here at the Royal Oak Music Theatre promoted only Romney, and an anonymous musical guest.

Reporters speculated that Kid Rock might be the mystery guest. His song "Born Free" has introduced Romney at nearly every campaign event since December, and the two men's shared affinity for all things Michigan seemed to offer a bridge between their wildly divergent worlds.

Tonight, with the politics behind them (there was a political rally here -- largely forgotten after the musical performance), Mitt and Ann Romney took in the performance from the front row, surrounded by Secret Service agents. They smiled and nodded along to the music, clapping to the beat and taking it all in.

Tomorrow, Michigan votes, and the tune could change.