Democrat Randy Perkins, Republican Brian Mast and independent Carla Spalding face off in a debate only on WPTV NewsChannel 5.
The candidates are vying for the District 18 seat being vacated by Democrat Patrick Murphy, who is running for the U.S. Senate against incumbent Marco Rubio.
This is one of the closest races in the country.
Heading into the election, Perkins has a significant lead over Mast in fundraising, but both candidates have been airing campaign ads since July.
District 18 includes St. Lucie and Martin Counties, and a portion of northern Palm Beach County.