In a major setback to the ruling Congress party in Telangana region, its state president D Srinivas was defeated on his home turf of Nizamabad urban constituency by a margin of 12,600 votes.
In a repeat of 2009 results, Y Lakshminarayana of the Bharatiya Janata Party retained the seat, which he had quit in favour of Telangana state.
Srinivas had express confidence that he would wrest the seat with the support of sizeable minority vote bloc but the aggressive campaigning by the TRS in support of BJP candidates coupled with a very low voter turnout dampened his expectations.
According to the latest results, the TRS has won six seats, the BJP has won one seat and the TRS was leading in five constituencies.
Commenting on the outcome, Congress MP from Nizamabad Madhu Yashki said the party would have to seriously ponder over the results of the by-poll.
He added the results showed there was a strong sentiment in favour of Telagana state.
Among other notable Congress candidates, former minister G Vinod was facing defeat in Chennur (Scheduled Castes) constituency of Adilabad district.
All hope is not lost, as former minister Mohammed Ali Shabbir is locked in a tight fight with A Ravinder Reddy of the TRS.
The use of ballot papers in the election has slowed down the counting process.
The TDP's lone seat is at stake as Vemulavada in Karimnagar district has been wrested by the TRS.
Ch Ramesh Rao, who had won the seat as TDP candidate last year, retained the seat as a TRS candidate. He was the only TRS legislator from Telangana to resign in support of Telangana state.
Senior Telugu Desam leader T Devender Goud said the victory of TRS in the by-elections was expected. He said the TDP leadership could not campaign for the party in the by-elections, as it was busy fighting against the Babili project of Maharashtra.