The East Ridge mayor's race has shifted from a two-person contest with the entry of current Mayor Brent Lambert.
Mayor Lambert, who recently lost a race for County Commission, picked up papers on Wednesday.
Vice Mayor Jim Bethune and citizen activist Frances Pope picked up earlier.
Mayor Lambert and Vice Mayor Bethune have often been on opposite sides on issues.
Mayor Lambert formerly had a solid 3-2 bloc, but there was a shift of power on the commission when Marc Gravitt went on. He often votes with Vice Mayor Bethune and Councilman Denny Manning.
Mayor Lambert finished third in the GOP primary for District 8 County Commission. Incumbent Tim Boyd won the primary and former Commissioner Curtis Adams was second.