The Samajwadi Party, which has 5 MPs, and RJD with 4 MPs may vote against the Lokpal Bill in the Rajya Sabha on Thursday.
Party sources said its 22 MPs, who walked out of the Loksabha before voting on the Lokpal Bill on Tuesday, said that their MPs may vote against the measure in the Upper House on Thursday.
Like SP, if BSP with 18 MPs and RJD with 4 MPs also oppose the bill and if decide to vote against it, then the government will have serious concerns over the fate of the bill's passage.
In the 243-member Rajya Sabha, Congress and its allies do not not have a majority with its number placed at 92 and needs the support of the MPs of these parties supporting the government from outside. At least a walk out by them could help the government but not not a vote against.
RJD sources said the bill was "doomed" because "nobody" wants it and the party may also vote against it.
BSP leader in Rajya Sabha Satish Chandra Mishra said the party has not not taken a final decision and its strategy will be revealed at the time of voting in the House.
But to say that the party MPs will walk out of the House is wrong, he said.
Congress' ally Trinamool Congress, which is part of the UPA government and has 6 MPs in Rajya Sabha, has moved amendments to the Bill that it considers encroaches on the federal structure of the Constitution and the states rights.
"We have already submitted our amendments. We are going to press for it," Mukul Roy, Trinamool leader and minister of state for shipping, told reporters in New Delhi.
The bill passed by Lok Sabha two days ago has provisions for setting up of Lokayuktas in the states with the consent of state governments.
Asked whether the six party MPs will vote against the bill, he said the question does not arise as of now.
"After the discussions and after amendments are over, the question of voting will arise. But till now, Trinamool is firm in its opinion that Part III of the bill be deleted from the original bill," Roy said.
"We are just pressing for the deletion of Lokayukta part, We have no problem with Lokpal part," he said, adding they are in favour of Lokayuktas but it should be done by states and not the Centre.
He said he and other party leaders have spoken to finance minister Pranab Mukherjee to sort out the issue.