A debate between U.S. Sen. Jon Tester and Republican challenger U.S. Rep. Denny Rehberg has been canceled with no plans to reschedule.

The cancellation is the result of scheduling conflicts, according to the Montana Broadcasters Association, the organization hosting the event.

The event was set for Sunday morning in Whitefish.

The debate was supposed to feature the two major candidates and Libertarian candidate Dan Cox of Hamilton.

Denny Rehberg's campaign announced last week that the congressman wouldn't be attending a debate, claiming that he was never formally invited. The MBA still planned to hold the debate, but then Wednesday announced the cancellation.

MBA disputes Rehberg's claim that he wasn't invited.

The Associated Press is reporting that the Tester campaign is accusing Rehberg of breaking his word by backing out, saying Rehberg is afraid to debate.  

Rehberg's campaign blames organizers for failing to make adjustments that would have allowed the congressman to attend. Rehberg had previously scheduled to travel to fundraising events out of state.

The three candidates debated for the first time June 16 in Big Sky. Plans are in the works for a Sept. 5 debate in Butte.