Dan Shores, John Chapman, Vince Cogliano and Mark Alliegro have all agreed to participate.
The winner of the Republican Primary will challenge Democratic incumbent Bill Keating in the November general election.
Former State Representative and Congressional Candidate Jeff Perry will moderate the debate with a group of GOP activists and panelists from across the Cape.
Doors open at 6 p.m. with the debate starting at 7 p.m.
The event is free and open to the public.
The primary is September 9.
To listen to interviews from the CapeCod.com Newsroom with all of the candidates, click here.