He started a 36-hour fast on Saturday but later turned it into an indefinite fast to exert pressure on Assembly Speaker P. Srinivas Reddy to disqualify the 12 MLAs who defected to the TRS.
Congress leaders have termed as "undemocratic" the action of the Speaker in merging the 12 Congress MLAs with the TRS Legislature Party.
Another leader and former Minister Ponnala Lakshmaiah joined Vikramarka in the indefinite fast on Sunday.
The Speaker, on June 6, had recognised the merger of 12 legislators, hours after they met him and made a request.
Congress party leaders have alleged that Chief Minister K. Chandrashekhar Rao had given a killer blow to democracy in the state by encouraging defections.
They described the TRS chief as "anti-Dalit", saying that he cannot bear to see Vikramarka, a Dalit, as the leader of the opposition.
Vikramarka alleged that Chandrashekhar Rao was indulging in "political terrorism".
He said the Speaker did not take action on Congress party's petitions for disqualifying the defectors but acted quickly for the merger after their numbers swelled to 12.
The merger brought down the Congress tally in the 119-member Assembly to six. The party may also lose the position of leader of opposition.
The All India Majlis-e-Ittehadul Muslimeen (AIMIM), which has seven MLAs, has decided to approach the Speaker seeking the leader of opposition status for the party.
( With inputs from IANS )