Dalit outfits here ran a postcard campaign against the Citizenship Amendment Act and sought a DNA-based National Register of Citizens.
The Purvanchal Sena, Asur Chatra Sangathan and the Bheem Army also urged the prime minister to withdraw the controversial citizenship law.
The campaign was launched on February 4 and around 500 postcards were posted to the prime minister on Wednesday.
Purvanchal Sena president Dhirendra Pratap said, "A DNA-based NRC will be better. At least, it will be known to everyone that who is the original resident of India and who are migrants."