Congress President Sonia Gandhi and Janata Dal (United) leader Sharad Yadav had visited the communist leader while he was on life support in the hospital.
Senior Communist Party of India (CPI) leader Ardhendu Bhushan Bardhan, who steered the party during the turbulent period of coalition politics at national level in 1990s, died in New Delhi tonight after prolonged illness.
Mr Bardhan, 92, is survived by son Ashok and daughter Alka. His wife, a professor in Nagpur University, died in 1986. Mr Bardhan was admitted to Delhi's GB Pant hospital after he suffered a paralytic stroke last month.
Dr Vinod Puri, Director and Professor of Neurology in G B Pant Hospital, said Mr Bardhan "died at 8:20PM. He had a brain stroke due to blockage in the middle cerebral artery. He was in comma".
Earlier in the day, Mr Raja said the condition of Mr Bardhan had "worsened" with his blood pressure levels falling.
"Condition of Comrade Bardhan has worsened today. He was put off ventilator yesterday and was able to breath normally. But today, his blood pressure (level) fell and his condition has turned very critical now," CPI national secretary D Raja said.
Mr Bardhan, who lived in the CPI headquarters in the national capital, was admitted to the hospital on December 7 after he felt uneasiness and lost consciousness.
Mr Bardhan has been a leading figure of the trade union movement and Left politics in Maharashtra and a key figure in fostering relations between the Congress-led UPA and the Left in the early 2000s.
Mr Bardhan entered the electoral politics in 1957 when he won as an Independent candidate in Maharashtra Assembly polls but there failed to achieve success in Lok Sabha and Rajya Sabha polls.
He later rose to become the General Secretary and then President of All India Trade Union Congress, the oldest trade union in India.
Among those who paid tributes to Mr Bardhan were Prime Minister Narendra Modi, Communist Party of India-Marxist general secretary Sitaram Yechury, BJP leader Mukhtar Abbas Naqvi and West Bengal Chief Minister Mamata Banerjee.