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In the voting that followed after the BJP walkout, Mr Kumar got all 160 votes. With Nitish Kumar having the support of 164 MLAs in the 243-member Bihar assembly, the test of majority was mostly a formality.
In his speech during the debate on the motion of confidence, Tejashwi Yadav -- chief of Rashtriya Janata Dal and Mr Kumar's new deputy, said the new partnership will be "historic". "This is a never-ending innings, it will be historic. Our partnership will be long. No one is going to be run out," Tejashwi Yadav said.
During the debate, the BJP's Tarakishore Prasad ripped into Nitish Kumar, his former boss, saying he has lost "political credibility".
The former Deputy Chief Minister mocked Mr Kumar's "personal ambition to become the prime minister despite not having the ability to become the chief minister on his own steam".
The assembly session started with Speaker Vijay Kumar Sinha, a BJP member, stepping down in response to a no-confidence motion against him by the Grand Alliance. The floor test was chaired by Deputy Speaker Maheshwar Hazari, who is from Mr Kumar's Janata Dal (United).
Hours before the trust vote, the homes of several RJD leaders -- Sunil Singh, Subodh Rai, Dr Faiyaz Ahmad and Ashfaque Karim -- were raided by the CBI in connection with a "land-for-jobs" scam dating back to party chief Lalu Yadav's tenure as Union Railway minister in the UPA government.
In Assembly, Tejashwi Yadav ripped into the BJP, saying, "Are you trying to say that all the property in the country belongs to Tejaswi Yadav? The person who brought the railways into profit is facing cases and those who are selling the railways and the country, nothing will happen to them".
Tejashwi Yadav also made several other strong remarks, accusing the BJP of using the Central investigating agencies whenever it is "scared". "A narrative is being created. If you join hands with the BJP, then you are Harishchandra (a king from mythology known for his honesty and truthfulness). Else you are a criminal, a rapist, and the ED and the CBI will be set after you," he said.
The majority test comes days after Nitish Kumar expanded his cabinet, where the biggest chunk of seats went to Tejashwi Yadav's Rashtriya Janata Dal. Of the 31 ministers in the cabinet, the RJD has 16, Nitish Kumar's JD(U) kept 11. Two Congress leaders, a leader of Jitan Ram Manjhi's Hindustani Awam Morcha and an Independent MLA have also become ministers.
Mr Kumar took oath as the Chief Minister of Bihar for the eighth time on August 10, a day after breaking away from the BJP. Sources said he had concerns that the BJP was plotting a repeat of the Maharashtra model -- where the Uddhav Thackeray government was dismantled by the rebellion by senior Shiv Sena leader Eknath Shinde who is now the Chief Minister.
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