Indiana’s three Republican U.S. Senate candidates – Reps. Luke Messer and Todd Rokita, and businessman Mike Braun – will meet Monday evening for the final debate before the May 8 primary.

That’s amid controversy that’s swirled around the event hosted by the nonpartisan Indiana Debate Commission.

Last month, Rokita said no to the Indiana Debate Commission. Commission President Gerry Lanosga says he was surprised.

“And disappointed, of course,” Lanosga says. “You know, this is the first time that’s happened in our ten years of doing debates.”

Then earlier this month, Rokita did an about-face, opting to join the debate. But he had harsh words for its moderator, Abdul-Hakim Shabazz. Rokita’s camp argues conservative commentator Shabazz isn’t a fair arbiter.

Lanosga says he’s confused by that – the debate’s questions come almost entirely from the public.

“The moderator’s role is to keep the candidates on track, sort of keep the trains running, and ask follow up questions closely related to the questions from the public,” Lanosga says.

Lanosga says he’s hoping for a substantive debate focused on policy issues, not personal attacks.