Republican Jeff Flake and Democrat Richard Carmona will square off in a debate Wednesday in the race to fill the U.S. Senate seat being vacated by retiring Sen. Jon Kyl.
The one-hour debate marks the first of three general-election debates the candidates will have before election day.
The other debates are scheduled for Oct. 15 in Tucson and Oct. 25 in Yuma.
Flake is a six-term congressman.
Carmona was surgeon general under President George W. Bush.
After the debate, former President Bill Clinton is scheduled to appear at a rally in Tempe for Carmona.
Voters can begin casting ballots on Thursday.
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