Senior Bharatiya Janata Party leader and former Bihar deputy chief minister Sushil Kumar Modi died on Monday night, the party said.
Modi, 72, had served as the deputy chief minister of Bihar from 2005 to 2013, and again between 2017 and 2020.
Prime Minister Narendra Modi and several senior leaders of various parties condoled the death of the BJP leader..
"The BJP family is deeply saddened by the news of the demise of former deputy chief minister of Bihar and former Rajya Sabha MP Shri Sushil Kumar Modi," the state unit of the party said in a post on X.
This is an irreparable loss for Bihar and the entire BJP family, it said.
He breathed his last at around 9.45 pm at the All India Institute of Medical Sciences in Delhi, hospital sources said.
According to party sources, he will be cremated on Tuesday in Patna.
Last month, the BJP leader took to X to announce that he was battling cancer for the last six months and will not be able to campaign in the Lok Sabha elections.
"I have told everything to Prime Minister Narendra Modi. I will always remain grateful and dedicated to the country, Bihar and the party," he had said in the April 3 post.
In his condolence message, the prime minister said Sushil Kumar Modi has played an invaluable role in the rise and success of BJP in Bihar.
"Strongly opposing the Emergency, he made a name for himself in student politics. He was known as a very hardworking and sociable MLA. He had a deep understanding of the issues related to politics. He also did a lot of commendable work as an administrator. His active role in the passage of GST will always be remembered," PM Modi said in a post on X.
Bihar Chief Minister Nitsih Kumar also expressed grief over the demise of Modi.
In a statement, Kumar said, "It's a personal loss for me. We were together during JP movement. His death has created a vacuum in the political arena of the country as well as in Bihar."
Union Minister Nitin Gadkari said the demise of Sushil Kumar Modi is an irreparable loss for Bihar and the country.
"I have personally worked with Sushil since the days of the Vidhyarthi Parishad. Sushil will always be remembered as a leader dedicated to his ideology. He has made a significant contribution to strengthening the party and the organization in Bihar. He worked for the development of Bihar throughout his life," he said.
Bihar BJP president and state deputy chief minister, Samrat Chaudhry said, "Heartfelt tribute to former deputy chief minister of Bihar and former Rajya Sabha MP Shri Sushil Kumar Modi ji on his demise."
Another Deputy CM Vijay Kumar Sinha said he would always be remembered for his organization skills, administrative understanding and his deep knowledge of social and political issues."
Condoling his death, West Bengal Chief Minister Mamata Banerjee said in a post on X, "Sorry to hear about the sad demise of Shri Sushil Kumar Modi, former deputy chief minister of Bihar. Our thoughts and prayers are with his family & friends. May the departed soul rest in peace."
Rashtriya Janata Dal leader Tejashwi Yadav also said he was extremely saddened to hear the news of Modi's death.
He described Modi as "our guardian, struggling and hardworking leader".
During his political career spanning over three decades, Modi held various positions, including MLA, MLC and member of Lok Sabha and Rajya Sabha.
He became an MLA for the first time in 1990 from Patna Central constituency and was made the chief whip of the BJP legislature party.
From 1996 to 2004, he was the leader of the opposition in the state assembly. He became a member of Lok Sabha in 2004 from Bhagalpur.
He gave up his Lok Sabha membership in 2005 and became a member of the legislative council, following which he was made the deputy chief minister while Nitish Kumar was the CM.
Modi was elected to the Rajya Sabha in 2020 and he retired earlier this year.