 -- Hillary Clinton's running mate, Virginia Sen. Tim Kaine, can add another job title to his resume: DJ.

On a campaign bus on a swing through Ohio, Kaine has put himself in charge of the entertainment during slow periods. He plugs his iPhone into the speaker system and even plays some tunes on his beloved harmonica, according to a campaign aide.

On Saturday night after a campaign stop in Youngstown, Ohio, Kaine and Clinton shared some pizza.

Then Kaine and his wife joined staff members on a separate bus to continue the late-night ride to Cleveland. During that trip early Sunday morning, Kaine broke out his harmonica. He previously told CNN that he was packing six harmonicas for the bus trip.

Kaine played "Wagon Wheel" by Old Crow Medicine Show, according to a campaign aide. When not playing tunes, he was choosing them. Some of the artists on Kaine's playlists included the Beatles, the Isley Brothers, Prince and the Rolling Stones.

Kaine is an admitted music lover. Friends have described him as being able to talk about any genre of music. He's reportedly played on stage with such musicians as Boyd Tinsley, Bruce Hornsby, Ricky Skaggs, Dan Tyminski and the Cary Street Ramblers.

Even before this campaign swing, the vice presidential candidate had shown his musical chops: Last Sunday -- days after he was named as Clinton's running mate -- he sang a solo in his church's choir.

Kaine has for years been a tenor in the choir at St. Elizabeth Catholic Church in Richmond, though he has admitted his political career has made it hard to make practices.

Backstage at last week's Democratic National Convention, Kaine also played his harmonica. The Clinton campaign released this photo showing the Virginia senator jamming.

Kaine's love of the harmonica has drawn an invitation to a duel from the frontman of Blues Traveler, John Popper.

So far Kaine hasn't responded to the challenge.