Mamata Banerjee's party on Thursday said it will abstain from voting in the Vice President election, in which the ruling BJP's candidate is Jagdeep Dhankhar, the Governor of Bengal.
The Vice Presidential election will be held on August 6. Jagdeep Dhankhar's opposition rival is Congress veteran Margaret Alva.
Bengal Chief Minister Mamata Banerjee's Trinamool Congress has delivered the latest blow to opposition unity after parties like the Shiv Sena and the JMM backed Droupadi Murmu, the presidential candidate of the BJP-led National Democratic Alliance (NDA).
Mamata Banerjee's nephew Abhijit Banerjee said the party had unanimously decided not to support either Mr Dhankhar or Margaret Alva.
"The question of supporting the NDA (BJP-led National Democratic Alliance) candidate doesn't even arise. The way the opposition candidate was decided without proper consultation and deliberation with a party which has 35 MPs in both the houses, we have decided unanimously to abstain from the voting process," the Trinamool Congresss MP told reporters.
Mr Dhankhar's elevation as Vice President of India will move him out of Bengal to Delhi, and for Mamata Banerjee, that is a huge win.
The Chief Minister and Mr Dhankhar have clashed relentlessly over the past three years, with Ms Banerjee accusing the governor of hounding her at the instance of the BJP at the centre.
Despite the hostile relationship, Mr Dhankhar is believed to have sought Ms Banerjee's support. The two met in Darjeeling recently and Assam Chief Minister Himanta Biswa Sarma was also present.
Mr Banerjee said most Trinamool MPs were against backing the opposition candidate.
"On one side is NDA's Dhankhar, on the other side is Margaret Alva. There was a consensus that with Dhankhar's conduct and heavy bias, his assault on the people of Bengal in the past three years...there is no way we can support the NDA candidate," Mr Banerjee said.
"On the other hand, the opposition candidate was decided without us being consulted. A senior leader reached out to Mamata Banerjee but only after the meeting," he added.
Trinamool spokesperson Derek O'Brien told NDTV: "We want opposition unity but the largest opposition party and the Communists can't cook up names and take us for granted. Treat us as equals. Don't take Trinamool for granted."
The Trinamool vehemently denied any tacit support to Mr Dhankhar, insisting that it could ideologically differ with opposition parties without diluting its anti-BJP stand.