BJP president Amit Shah on Wednesday tore into the Opposition for questioning EVMs, terming their demands “unconstitutional” and accusing them of “tarnishing” India and its democracy, on a day the party geared up for unprecedented post-counting celebrations.

Shah claimed that the Opposition parties were rattled by imminent defeat and so were questioning the country’s electoral process.

The BJP chief posted a series of tweets targeting the Opposition’s demand that VVPAT slips be tallied with EVM records in a specific number of booths before the counting of votes, claiming such a move was not possible without the consensus of all parties.

Referring to an Opposition delegation’s visit to the Election Commission office on Tuesday with the request for such tallying, Shah tweeted: “Just two days before the counting of votes, the demand for change in the electoral process by 22 Opposition parties is totally unconstitutional because such a decision is not possible without the consensus of all the parties.”

The BJP boss wondered why Opposition parties assumed power without questioning EVMs when they won elections. He referred to the “historic” mandate of 67 out of 70 seats the AAP got in Delhi. “If EVMs are suspect, then why did these parties assume office?” Shah tweeted.

He said the allegations of EVM tampering picked up after the sixth phase of polling and the “noise got shriller after the exit polls”, accusing the Opposition of blaming the machines after sensing defeat.

The BJP headquarters in New Delhi has begun decking up for massive celebrations on Thursday, confident of a “bigger victory than the one in 2014”.

A team from national broadcaster Doordarshan was seen at the sprawling party headquarters planning placement of cameras at strategic points. Prime Minister Narendra Modi is scheduled to reach the headquarters after the trends become clear by evening.

BJP insiders said the Prime Minister was so confident of a “big victory” that he was preparing to restart his monthly radio address Mann Ki Baat on May 26, as he had promised while suspending it in view of the elections.

Although most party leaders exuded confidence about the BJP winning more than 300 seats, some others exercised caution.

“I’m keeping my fingers crossed,” a leader said, fearing that the BJP might not get majority on its own and would have to depend on allies.