The Montana Broadcasters Association has announced the Rehberg-Tester senate campaign debate in Whitefish has been canceled.

Rep. Denny Rehberg’s campaign announced last week that Rehberg wouldn’t attend the debate with Sen. Jon Tester at Grouse Mountain Lodge in Whitefish on Sunday, June 24.

Rehberg, a Republican, is challenging Tester, the incumbent Democrat, in this year’s U.S. Senate race. Political observers have already said the race could become the most expensive in Montana history.

The debate between the two had been promoted by the Montana Broadcasters Association, which will be holding their annual convention in Whitefish.

Rehberg’s campaign, however, said the Montana Broadcasters Association never formally invited Rehberg to the debate.

The Montana Broadcasters Association disputed that claim and planned to hold a debate with Tester and Libertarian candidate Dan Cox at 9 a.m.

All three senate candidates debated at the Montana Newspaper Association’s annual convention in Big Sky on June 16.

Rehberg’s campaign says they are finalizing plans for a debate on Sept. 5 in Butte sponsored by NBC Montana and AARP Montana. Tester has expressed interest in that debate.