Seventeen political parties, including the Trinamool Congress, are planning to approach the Election Commission and demand that the 2019 Lok Sabha elections be held on ballot papers, PTI reported on Thursday.

“This is a matter on which all Opposition parties agreed,” Trinamool Congress leader Derek O’Brien told reporters. “We are planning to meet next week.”

Trinamool Congress chief and West Bengal Chief Minister Mamata Banerjee urged the Opposition parties to unite on the matter when she met their leaders in Parliament on Wednesday. Banerjee was there to invite them for her planned rally in Kolkata on January 19.

The Shiv Sena, an ally of the Bharatiya Janata Party, may also join forces with the Opposition on the matter, NDTV reported quoting unidentified officials. The Opposition parties are expected to meet in Ghulam Nabi Azad’s office in Parliament on Monday morning, and send a delegation to the poll panel later that week.

The Opposition has raised doubts about the infallibility of electronic voting machine a number of times in the recent past. At its plenary session in March, the Congress expressed concerns about the machines being vulnerable to manipulation. However, Chief Election Commissioner OP Rawat has blamed the parties for making voting machines a scapegoat for their electoral defeats.