India's ruling coalition, the United People's Alliance (UPA), Tuesday was again in trouble with its second largest constituent - West Bengal's ruling Trinamool Congress which said it will not back the Congress nominee for the Rajya Sabha or upper house of parliament polls in the eastern Indian state.

"The Trinamool Congress has decided not to support the Congress nominee in West Bengal for the upcoming Rajya Sabha polls," state Congress chief and Member of Parliament Pradip Bhattacharya said.

He said "As far as I know, the Trinamool has decided not to support our candidate. I don't know what will happen later on."

"I have placed the list of probable candidates of the Congress before Pranabda (Union Finance Minister Pranab Mukherjee) and Shakeelji (Congress General Secretary Shakeel Ahmed)," he added.

This means Trinamool Congress Chief and West Bengal Chief Minister Mamata Banerjee is sending a clear signal to the Congress high command that unless Union Finance Minister Pranab Mukherjee during the budget on March 16 allocates special funds for the state, she was ready to break the alliance with Congress and quit the UPA.

On March 30, five Rajya Sabha members from the state would be elected to fill up vacancies arising on April 2.

According to the arithmetic in the assembly, Trinamool with 185 seats in the 294-member state Assembly is in a comfortable position to send three members to the upper house of parliament. The Left Front with 61 members can win one seat.