HELENA, Mont. (AP) — U.S. Rep. Denny Rehberg's campaign says the Republican congressman won't be attending a weekend debate with U.S. Sen. Jon Tester.

The campaign says it was never formally invited by the debate hosts, and says it never confirmed participation.

Greg MacDonald with the Montana Broadcasters Association disputes the claim, but says the debate will go on Sunday morning between Tester, the incumbent Democrat, and Libertarian candidate Dan Cox of Hamilton.

All three just completed a debate Saturday in Big Sky.

The Rehberg campaign also said Monday it is finalizing plans to accept a Sept. 5 debate in Butte sponsored by NBC Montana and AARP Montana. Tester has already expressed a desire to accept that debate offer.

The Senate race is expected to remain a high-profile battle through the election season.