Accusing the Election Commission of working under political pressure, the Aam Aadmi Party (AAP) on Saturday said it was "delaying the EVM hackathon".
The allegation came hours before the Election Commission's scheduled demonstration on the working of Electronic Voting Machines (EVMs) and VVPATs to allay fears that these can be tampered with in favour of a particular candidate or party.
AAP leader Sanjay Singh said the people have serious questions regarding EVM tampering which should be answered.
"EC should conduct a hackathon where the experts from AAP can prove before the EC officials that EVMs can be hacked," he said.
"I want to know under whose pressure the Election Commission is delaying its promise to conduct an EVM hackathon?"
He said 18 political parties have met President Pranab Mukherjee and the EC and demanded the use of paper ballot instead of EVMs.
The poll panel had announced after an all-party meeting on May 12 that it will hold the challenge to let political parties prove their claim that the EVMs used in the February-March assembly elections were, or could be, tampered with.
It had also announced that all future elections will be held using VVPAT (Voter-verifiable paper audit trail).