However, most incumbents have suggested recently that they plan to seek re-election.
The deadline to qualify is noon April 3.
As it stands, Cheri Siler, a Democrat and instructional coach in the Knox County school system, picked up a petition to run for the 7th District state Senate seat currently held by Republican Stacey Campfield.
Knox County Commissioner Richard Briggs, a Republican, also is expected to challenge Campfield, but he did not pick up a petition yet.
The state primaries are set for Aug. 7 with the general election is scheduled for Nov. 4.
Also on Friday, state Rep. Gloria Johnson, a Democrat, picked up a petition to seek re-election for her District 13 seat, as did state Rep. Steve Hall, a Republican and the District 18 House incumbent.
The following state seats also are up for re-election: 5th District Senate (Randy McNally, R); 14th District House (Ryan Haynes, R); 15th District House (Joe Armstrong, D); 16th District House (Bill Dunn, R); 19th District House (Harry Brooks, 19); and 89th District House (Roger Kane, R).
Friday also marked the first day that Town of Farragut candidates could pick up nominating petitions, although no one did. The mayoral post and two alderman seats are up for re-election. The seats are non-partisan. That election is also set for Aug. 7.
Candidates need to meet certain qualifications to run for office. In addition, they need 25 signatures from registered voters who can vote in that particularly race.