HELENA (AP) — The Montana Broadcasters Association has canceled a debate in the state’s high-profile U.S. Senate race that had been scheduled for Sunday morning in Whitefish.

The organization cited “scheduling complications” that prevented Republican U.S. Rep. Denny Rehberg from attending.

Incumbent Democratic U.S. Sen. Jon Tester and Libertarian candidate Dan Cox of Hamilton originally were scheduled to debate without Rehberg. The broadcasters, however, announced Wednesday evening that they have canceled the event since all three candidates cannot attend.

The Tester campaign is accusing Rehberg of breaking his word by backing out. Rehberg’s campaign blames organizers for failing to send a timely invitation and then failing to make adjustments that would allow the congressman to attend later in the day.

Rehberg previously had scheduled a travel day Sunday to go from a fundraiser in Wyoming today to one in St. Louis on Monday, his campaign said. Rehberg canceled his Monday event so he could debate later in the morning on Sunday — giving him enough time to return to the state from the Saturday event in Wyoming.

But that offer to debate later than the original 9 a.m. time slot was rejected by the broadcasters group. Further negotiations between the two sides fell apart.

The Rehberg campaign said it will schedule other events or personal time for Sunday, but has not done so yet.

Tester’s campaign said that the Democrat will use the time Sunday to load a truck with wheat at his Big Sandy farm for shipment to South Dakota.

It would have been the second Senate debate following a Saturday event in Big Sky. The candidates say they are working on plans for a Sept. 5 debate in Butte.