The cabinet nod to a Bill providing quota in promotion to SC/STs in government jobs on Tuesday left some unease within the Congress with a section fearing that the move may erode the party's support base.
A senior leader of the party felt that the decision would leave the middle class unhappy.
There is a feeling that the Constitution Amendment Bill would in all probability not be passed during the current Monsoon Session of Parliament and even if it did, the possibility of the Supreme Court striking it down could not be ruled out, the leader said.
The Bill will require two-third majority of the members present in both the Lok Sabha and the Rajya Sabha for passage.
The cabinet decision has already been criticised by the Samajwadi Party, which alleged that the government had done it to divert attention from the coal block allocation controversy.
The Supreme Court has already quashed the constitutional amendment four times, SP leader Ram Gopal Yadav told reporters outside Parliament on Tuesday.
BSP leader Mayawati, who has been on the forefront on this demand, met BJP leaders Sushma Swaraj and Arun Jaitley after the Cabinet nod to seek their support for passage of the Bill during the ongoing Parliament session.
The previous Uttar Pradesh government headed by Mayawati had provided reservation benefits for SCs, STs in promotions to higher posts in government jobs.
However, the Supreme Court on April 28 quashed it, terming it as unconstitutional and done without any sufficient data.