Shah attacked the alliance in a series of tweets, a day after Prime Minister Narendra Modi sought to corner the alliance leaders by accusing them of plotting to give away a share in the existing reservation to a particular community, a reference to Muslims.
"Congress in 2012 UP polls had promised 9 per cent quota to minorities. Nitish and Lalu are with Congress today, so I want to ask them if they will do it by taking away the share of Dalits and backward castes as the Supreme Court has fixed the limit of reservation at 50 per cent?" he said.
BJP also cited its string of victories in local polls, the latest from Goa, to claim that the nation's mood was in its favour and that it will win assembly elections in Bihar, where it is locked in a keen contest with the grand alliance.
Union Minister Venkaiah Naidu also rejected the opposition allegation that Narendra Modi tried to communalise the campaign by claiming the grand alliance wanted to give quotas to Muslims by shaving off five per cent reservation enjoyed by the existing beneficiaries, saying the issue was raised by RJD's Lalu Prasad and JD(U)'s Nitish Kumar and the Prime Minister had only countered them.
BJP chief Shah also tweeted to congratulate party workers on the Goa victory.
"I congratulate Karyakartas and Goa BJP unit on sweeping Goa municipal polls. I also thank people of Goa for showing their faith in BJP," Shah said.