The Telangana Rashtra Samithi, which has four members in the Lok Sabha, withdrew support on Saturday to the United Progress Alliance government, a move that is unlikely to affect the ruling coalition's stability as it has a comfortable majority in the House.
The TRS, which fought the 2004 general election in alliance with the Congress, withdrew support after not getting a commitment from the Central government on carving out a separate Telangana state from Andhra Pradesh.
The TRS alleged that the Manmohan Singh government -- which has the support of around 330 MPs in the 545-member Lok Sabha -- had failed to keep its promise on the separate Telangana state.
Party chief K Chandrasekhara Rao, who earlier resigned as Union labour minister as well as from the Lok Sabha, told reporters that he has sent a letter to President A P J Abdul Kalam, withdrawing TRS' support to the UPA government with immediate effect.
'Since the UPA government has failed to keep its promise made in the Common Minimum Programme on the formation of the separate Telangana state even after achieving clear consensus, as a protest, the TRS is withdrawing its support to the UPA government with immediate effect', the letter said.
The TRS decision to snap ties with the UPA caps the tumultuous relations between them over the past two years.
Rao said the by-poll to Karimnagar constituency, which he had quit, would be a 'referendum' on the Telangana issue and challenged the Congress to face the electoral battle.
"It will reflect the mood of the people of Telangana. Karimnagar will prove what is what," he said.
Asked specifically whether he would contest the by-poll, he said, "Most likely, I should contest. But I should not announce it all alone. It has to be formally announced by the party."
Launching a broadside at the Congress, Rao alleged that the party has manipulated the 'clear consensus' that emerged in favour of a separate Telangana state.
Seeking to buttress his claims, he said the total number of MPs supporting the demand amounted to about 400. This included members of the NDA, almost all parties of the UPA and many smaller parties.
Pooh-pooing the Congress argument that it could not count only on the support of the Bharatiya Janata Party, which has unequivocally backed the creation of a separate state, Rao wondered how the Congress could reject the support of the main opposition party.
He dared the Congress to contest the Karimnagar by-poll, saying, "I welcome them to come and contest. That is the reason for my withdrawing support. I am sounding the war bugle now."
Alleging that the Congress lacked a policy to run the coalition government, he claimed that most of its partners were unhappy.
Asked if he would join the NDA, Rao kept his cards close to his chest, saying, "What will happen in the future I can't say now."
Seeking to project himself as the leader of several parties demanding separate states, he said, "We will stir up separate state agitations in Vidarbha, Bundelkhand and other regions. I was elected convener of a committee to fight for separate states at a meeting held in Delhi."
Earlier in the day, Rao said after a meeting with Lok Sabha Speaker Somnath Chatterjee that his resignation from the Lower House has been accepted.