The party's Rajya Sabha MP had written to Prime Minister Narendra Modi on Monday, saying he would be "constrained to undertake an indefinite fast" if immediate steps were not taken to set up the plant.
Mr Ramesh wrote the letter five days after the Centre, citing a Steel Authority of India Limited (SAIL) feasibility report, told the Supreme Court that it was not "financially viable" to construct a steel plant at Kadapa.
The MP today alleged that the Centre was blocking setting up of the plant, saying it was not viable.
He vowed to continue the protest till the Centre conceded the demand.
Andhra Pradesh Legislative Council member M Ravindranatha Reddy too joined the MP in the fast.
Both leaders hail from Kadapa district.
Mr Ramesh had earlier said he would go on a 'fast-unto-death' in Kadapa district from June 24.
Union Steel Minister Chaudhary Birender Singh has reportedly said the Centre had never said it was against setting up of the steel plant.
BJP MLC Somu Veerraju said the TDP was trying to politicise the issue and maintained that the Centre was ready to set up the plant.
A formal announcement in this regard would be made soon, he added.
The proposed steel plant is emerging as another point of contention between the Centre and the TDP, which had in March pulled out of the NDA government over its refusal to grant special status to Andhra Pradesh.
TDP MP Jay Galla had last week accused the central government of misleading the people of Andhra Pradesh on the issue.
The party has been accusing the PM Modi government of not releasing enough funds for the Polavaram irrigation project and Amravati, the under-construction ultra-modern state capital.
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