Arvind Kejriwal-led Aam Aadmi Party has suffered a major setback with Rajya Sabha Chairman CP Radhakrishnan on Monday accepting the merger of seven of its MPs with the BJP.The latest party-wise tally on the Rajya Sabha website now shows AAP’s numbers in the house down to three from the previous ten, and BJP’s numbers up from 106 to 113. The ruling NDA’s strength in the house is up to 148 from the previous 141.The BJP on its own is now close to the majority mark of 123 in the Rajya Sabha. RS sources told The Tribune that the chairman took legal opinion on the letter of merger with BJP signed by seven AAP members, who form two-thirds of the strength of the AAP legislature party in the Rajya Sabha.These MPs are Raghav Chadha, Sandeep Pathak, Swati Maliwal, Harbhajan Singh, Vikramjit Sahney, Ashok Mittal, and Rajender Gupta. All have signed the defection letter and consented to merging with the BJP, RS officials said.The RS chairman found the letter in accordance with the Tenth Schedule of the Constitution, which permits a merger if two-thirds of the members of a party consent to one. AAP had meanwhile written to Chairman Radhakrishnan yesterday, demanding disqualification of the MPs and citing a violation of the Tenth Schedule, which details the anti-defection law.AAP has cited legal experts, including Kapil Sibal, to say that for the merger to be effective, it must be preceded by the merger of the political parties, followed by the legislature party, and not the other way around.However, in Maharashtra, Shiv Sena factions led by Eknath Shinde and NCP factions led by the late Ajit Pawar had earlier broken away from their parent parties by moving away with two-thirds of the MPs. Later, these factions got the main party election symbols as well.