He said Congress president Mallikarjun Kharge and leader of Opposition in the Lok Sabha Rahul Gandhi had jointly written to Modi on 20 August, raising objections to the existing format and calling for the questionnaire to be scrapped.
The two leaders have demanded that a fresh questionnaire be prepared using a certified list of castes, Ramesh said, adding that such an approach would reduce the possibility of multiple spellings and variations for the same community being recorded separately.
The Congress has pointed to caste surveys conducted in Telangana and Bihar as examples of how a pre-prepared and certified list could be used to streamline the exercise.
The party has also sought extensive consultations with political parties, experts and the public before finalising a new questionnaire.
Ramesh said the Congress has intensified its nationwide campaign on the issue, holding 17 press conferences across the country over the past four days.
The party is reiterating its demand that the caste census be conducted in a manner that produces accurate and usable data, which it says is essential for framing policies aimed at social justice.
Ramesh also said the Congress had not received a response from the prime minister to the 20 August letter, despite the concerns raised by Kharge and Gandhi.
The dispute over the questionnaire comes as the Congress seeks greater clarity and standardisation in the caste enumeration process, while pressing the government to consult political parties, experts and the public before proceeding with the exercise.
With PTI inputs