The Aam Aadmi Party suffered its severest blow on Monday as Rajya Sabha Chairman CP Radhakrishnan officially accepted and notified the merger of seven of its defected MPs with the BJP.The names of the seven MPs — Raghav Chadha, Sandeep Pathak, Swati Maliwal, Harbhajan Singh, Vikramjit Sahney, Ashok Mittal and Rajinder Gupta — now feature in the BJP parliamentary party segment on the Rajya Sabha party-wise tally.The move, which AAP has vowed to fight politically and legally, has powered the BJP’s numerical strength in the Rajya Sabha from 106 to 113.The BJP-led NDA government, meanwhile, welcomed the new entrants, with the Parliamentary Affairs Minister saying they had bid goodbye to the “tukde tukde INDI Alliance and chosen the constructive politics represented by Prime Minister Narendra Modi”.The overall numbers of the ruling NDA have now soared from 141 to 148 in the 245-member House where 123 is the majority mark.Rajya Sabha sources said the Chairman took a legal opinion on the seven-member AAP bloc’s declaration to merge with the BJP. All seven MPs, who form a two-thirds of the AAP’s 10-MP strength in the House, signed the letter of merger, which was accepted today.After this development, AAP is down to just three members in the House — Sanjay Singh, ND Gupta and Balbir Singh Seechewal.Rajya Sabha officials said the letter was found in order under the Tenth Schedule of the Constitution (anti-defection law), which permits a merger if two-thirds of the members of a party consent to join another.AAP had yesterday written to Chairman Radhakrishnan demanding disqualification of the MPs, citing violation of the Tenth Schedule.AAP cited legal experts to say that the merger, to be effective, must be preceded by the merger of political parties followed by the legislature party and not the other way round.However, in Maharashtra earlier, the Shiv Sena faction led by Eknath Shinde and the NCP faction led by the late Ajit Pawar broke away with two-third members from the respective parent parties.These factions were recognised by the Speaker of the Assembly and later bagged the original party election symbols too.But AAP insists that the merger of its MPs with the BJP is unconstitutional.AAP’s Sanjay Singh said, “The Rajya Sabha Chairman has taken cognisance of the letter submitted by those seven MPs, and based on that, he has accepted the merger. The objection raised by us and the disqualification we demanded based on the Tenth Schedule of the Constitution, has not even been considered. I am hopeful that when our letter will be considered, the Chairman will rule in favour of the Constitution and democracy, and disqualify the membership of these seven MPs,” Singh said.He said if the decision of the House Chairman was adverse, AAP would approach the court.Senior Supreme Court lawyer Kapil Sibal is guiding AAP in the matter.He had earlier said such petitions take years to settle and by then further political damage is not ruled out.“These matters can take up to five years. By then who knows what may happen. A split in the Punjab AAP may also be possible,” Sibal said.Sibal added that the constitutional provision was for the political party to merge with another and then its legislature party to merge with the new party.“Here the reverse is happening. Parties haven’t merged but the legislature party in the Rajya Sabha has. This can’t be. This is against the Constitution Tenth Schedule and the anti-defection law. But the problem is this is not about law, this is about politics,” Sibal said.