"President's order disqualifying the 20 AAP MLAs is complete miscarriage of natural justice. No hearing, no waiting for High Court's order. It is Tughluqshahi (Tughlaqshahi) of the worst order," Mr Sinha tweeted.
The AAP described the move as politically motivated and termed the disqualification as "murder of democracy".
"President's order to disqualify AAP MLAs is unconstitutional and dangerous for democracy," AAp leader Aashutosh tweeted. The party said it would go to the Supreme Court if need be. The high court will hear their appeal against disqualification tomorrow.
The Election Commission on Friday asked President to disqualify the 20 lawmakers for holding "de facto the office of parliamentary secretaries from March 13, 2015 to September 8, 2016".
AAP also alleged that the disqualification move was Chief Election Commissioner AK Joti's "parting gift to PM Modi". Mr Joti is retiring on Monday.
The AAP says the 20 legislators were acting as parliamentary secretaries assisting Delhi government ministers in running their offices, but were not receiving any salary for the work.
The opposition has called for Mr Kejirwal's resignation after the mass disqualification of legislators. The disqualification of the 20 lawmakers will, however, not dent AAP's majority in the Delhi assembly, which has 66 seats in 70-member assembly.