CPI (M) state secretary T Veerbhadram said the party had decided to field its candidate as the efforts by Congress to avoid a contest were not succeeding.
Sudarshan Rao will be the CPI (M) nominee.
The poll is necessitated by the demise of sitting Congress MLA R Venkata Reddy. Congress had appealed other parties to let his wife, Sucharita Reddy, get elected unopposed.
TDP and YSRCP agreed not to put up candidates. But the ruling TRS, however, announced the candidature of Roads and Buildings Minister T Nageswara Rao.