Libertarian Marc Victor is also in the debate.
Kelly, a retired astronaut and Navy pilot, was elected in 2020 to finish the remainder of the late Sen. John McCain's term and is now running for a full six-year term.
The Arizona race is one of a handful of contests that Republicans targeted in their bid to take control of what is now a 50-50 Senate. The debate comes less than a week before early and mail voting begins, the methods chosen by at least 80 percent of voters in recent elections.
The debate starts at 6 p.m. PT on Arizona PBS