The Maha Vikas Aghadi - thumped last week in the Maharashtra election - is planning a national protest against the credibility of EVMs, or electronic voting machines, which it blames for its defeat.
The MVA - fronted by the Congress and the Shiv Sena and NCP factions led by Uddhav Thackeray and Sharad Pawar - also plans to move the court to return to ballot papers.
Mr Thackeray and Mr Pawar met defeated MVA candidates Wednesday to form legal teams, at the state and national levels, to address the longstanding concern for opposition parties.