- Sharad Yadav had opposed Nitish Kumar's decision to partner BJP
- JDU had moved against him saying he has given up party membership
- Another JDU leader Ali Anwar who had followed suit disqualified too
The order said Mr Yadav had "voluntarily given up his membership of the political party, Janata Dal (United) by which he was set up as a candidate for election to the Rajya Sabha" and has "incurred disqualification".
Another JD(U) member, Ali Anwar, also was also disqualified for following Mr Yadav's lead and indulging in "anti-party activities".
The application from JD(U)'s leader in house RCP Singh came after weeks of acrimony. The founder-member of JD(U) -- who had yielded the party leadership to Nitish Kumar last year -- had irked the Chief Minister with his public disapproval after he ended the Grand Alliance with Lalu Yadav and the Congress in July and formed a new government in partnership with the BJP.
Mr Kumar had blamed it on corruption cases against Lalu Yadav and his son, Tejashwi Yadav, who was Deputy Chief Minister of Bihar. "The atmosphere had become such that it was impossible to work," he had said.
But Sharad Yadav had spoken out against the move regularly, accusing Nitish Kumar of being power hungry and betraying the mandate of the people of Bihar, who voted in the "Grand Alliance" in 2015.
But the final break came after Mr Yadav defied party command and attended a huge anti-BJP rally in Patna in August. He shared dais with Lalu Yadav and in his address, promised to work for a pan-India Grand alliance against the BJP and criticized Nitish Kumar again.
Within hours, JD(U) spokesperson KC Tyagi said Mr Yadav's action made for a fit case for disqualification. The party said it would appeal to the Rajya Sabha chairman and enclose Mr Yadav's speech at the programme to back up its claims.
Mr Yadav, meanwhile, claimed he was the "real JD(U)" and would contest the coming elections in Gujarat in alliance with the Congress. But his appeal for the party's election symbol, the arrow, was turned down by the Election Commission.
He has said that he remains committed to a front of 17 parties that are trying to work together to fight the BJP in parliament and prevent a return of the BJP in the 2019 general elections.