Do you know where Rep. Denny Rehberg (R-Mont.) will be on Saturday evening? If so, you could win Pearl Jam tickets.

The congressman said this week he would be unable to participate in the Montana Broadcasters Association's Sunday morning debate between U.S. Senate candidates, saying he never received the invitation. The MBA subsequently decided to cancel the debate.

Rehberg is running to unseat Sen. Jon Tester (D-Mont.), who had agreed to participate, as had Libertarian Party candidate Dan Cox.

The Tester campaign is itching to know what Rehberg will be doing Saturday night and why it would have prevented him from attending the now-canceled Sunday morning event, so it's offering two free Pearl Jam tickets to the first person who finds out. Tester spokesman Aaron Murphy said the congressman himself is eligible to win the contest, provided he's interested in divulging his whereabouts.

Rehberg's campaign did not immediately return a request for comment.

The tickets are to Pearl Jam's Sept. 30 concert in Missoula, Mont. Tester is also raffling off the chance for one of his contributors and a guest to watch the entire show on stage in recliners.

The band's bassist, Jeff Ament, is a native Montanan who backs Tester.

The Tester campaign has set up a special email account at concert [at] jontester [dot] com for anyone with information on Rehberg's Saturday evening whereabouts.

UPDATE: 10:45 p.m. -- KXLF reports that Rehberg will be in Wyoming on Saturday for a campaign event with Sen. John Barrasso (R-Wyo.). Rehberg's campaign maintained that it never received the invitation for the broadcasters' debate, and then attempted to get event organizers to reschedule for Sunday. The organizers declined and canceled the debate.

"Congressman Dennis Rehberg backed out of this debate because his priority is cashing the checks of out-of-state special interests, not addressing the issues that matter to Montana families," responded Tester campaign manager Preston Elliott. "After 12 years in Washington, Congressman Rehberg has forgotten who he works for.”

Also on HuffPost: