Four Northeast Mississippi counties also have election runoffs for other offices.
A special election for Senate District 19 will be on ballots in DeSoto County, and one for House District 52 will be on ballots in parts of DeSoto and Marshall counties.
Voters are choosing successors for former Sen. Merle Flowers of Southaven and former Rep. Tommy Woods of Byhalia. The two Republicans resigned this year.
Winners will serve the final three years of the four-year terms.
The Senate runoff is between optometrist David Parker of Olive Branch and first-term state Rep. Pat Nelson of Southaven.
The House runoff is between Marshall County planning board member Bill Kinkade of Byhalia and contractor Jeremy Bryan of Barton.
Marshall County also features a runoff for District 3 election commissioner between Virginia Armour and Clista Ash.
Other Northeast Mississippi runoffs include:
• Alcorn County – Election commissioner, District 3, Jimmy Harwood and Billy W. Bearden.
• Calhoun County – Chancery clerk, Romona Tillman and Susanne Wade.
• Tippah County – South Tippah School Board, District 3, Wayne Jumper and Keith Clark.
In all races, polls open at 7 a.m. and close at 7 p.m.