The demonstration, scheduled for Thursday, follows a Tuesday surge in opposition activity when Congress leader Rahul Gandhi and several MPs were briefly held by Delhi police before being released.
The Indian National Developmental Inclusive Alliance convened a luncheon meeting chaired by Congress president Mallikarjun Kharge on Wednesday, where the parties agreed to march together.
Three air‑conditioned buses were arranged to ferry the MPs from the centre of the city to a staging point on Ashoka Road, a two‑kilometre walk from the iconic Jantar Mantar.
Sit‑in begins at dusk; protestors will now gather near the Shangri‑La hotel demanding the resignation of Chief Election Commissioner Gyanesh Kumar.
Witnesses say chants echo through the streets, while Delhi Police has increased its presence, monitoring the event closely.