Sharad Yadav launched his own party in 2018, but merged it with RJD two years later.
Former Union Minister and one of the country's most prominent socialist leaders, Sharad Yadav, died on Thursday. The 75-year-old was ailing for a long time and had collapsed at his home in Delhi on Thursday. A statement from Gurugram's Fortis Memorial Research Institute – where he was taken immediately -- said Mr Yadav was brought to the emergency ward in an unconscious and unresponsive state.
"On examination, he did not have any pulse or recordable blood pressure. He underwent CPR as per ACLS protocols. Despite best efforts, he could not be revived and was declared dead at 10.19 pm," the statement said.
Starting politics as a student leader, Sharad Yadav had aligned himself with the anti-Congress camp and later became involved in JP movement. For most of his life, he remained a key presence in the opposition. He, however, reconciled both with the Congress and great political rival Lalu Yadav and was instrumental in crafting the Grand Alliance after the 2015 assembly elections in Bihar.
Sharad Yadav served as a minister in the Atal Bihari Vajpayee government in the late '90s and the VP Singh government in 1989.
A three-time member of Rajya Sabha, he was elected to the Lok Sabha seven times. The founder-member of Bihar's ruling Janata Dal United, he quit after Chief Minister Nitish Kumar ended the Grand Alliance and joined hands with the BJP.
In 2018, he launched his own party, the Loktantrik Janata Dal, but merged it with Lalu Yadav's Rashtriya Janata Dal two years later, saying it was the "first step towards a united opposition".
"Pained by the passing away of Shri Sharad Yadav Ji. In his long years in public life, he distinguished himself as MP and Minister. He was greatly inspired by Dr. Lohia's ideals. I will always cherish our interactions. Condolences to his family and admirers. Om Shanti," tweeted Prime Minister Narendra Modi.
"I am saddened by the news of the untimely demise of Mandal Messiah, senior leader of RJD, great socialist leader and my guardian respected Sharad Yadav ji. I am unable to say anything. Had a conversation with mother and brother Shantanu. In this hour of grief, the entire Samajwadi family is with the family members," tweeted Tejashwi Yadav.
"Sharad Yadav was my political guardian. He had a big role in making me the Deputy Chief Minister. Bihar will never forget his contribution," Bihar's former Deputy Chief Minister Sushil Modi tweeted.
Congress chief Mallikarjun Kharge also tweeted his condolences. "Am saddened by the death of Sharad Yadav, former president of JDU and senior leader of the socialist stream of the country. Serving the country as a former Union minister and an outstanding parliamentarian for decades, he strengthened the politics of equality," read a rough translation of his Hindi tweet.
From his hospital bed in Singapore, Lalu Yadav said in a video message that though he had many differences with Sharad Yadav, it "never resulted in any bitterness".
"He, besides late Mulayam Singh Yadav, Nitish Kumar and myself, learnt politics of socialism from Ram Manohar Lohia and Karpoori Thakur," said Mr Yadav, who has recently undergone a kidney transplant.
"On many an occasion, Sharad Yadav and I fought with each other. But our disagreements never led to any bitterness," said the RJD chief.