The order to this effect was passed by Justice Sri Kant Tripathi, who directed the MPs to file their counter-affidavits within four weeks while fixing August 24 as the next date of hearing in the case.
The election of Gandhi, who was detained under the stringent National Security Act for his alleged hate-speech prior to the polls, has been challenged by his maternal uncle V M Singh, who was fielded by the Congress as its nominee from Pilibhit constituency.
Rajnath Singh's election has been challenged by Samar Singh, who had contested from Ghaziabad as an independent candidfate.
Others who have been issued notices by the court are BSP MPs Kapil Muni Karwaria (Phoolpur) and Gorakhnath Pandey (Bhadohi), besides Samajwadi Party's Ramkishun (Chandauli).