The people of Bihar, who were fed up with the misrule of Lalu-Rabri dispensation, threw their weight behind Nitish-led NDA and the 15 year old RJD regime came to an end.
Once Nitish became Chief Minister, he became very ambitious. He played all the tricks to create a committed vote bank of his own through EBC and Mahadalit cards that he started playing so smartly.
The consecutive victory for Nitish in 2010 assembly elections made him over-confident and he thought that he could replicate the winning combination of Lalu with the support of Muslims.
Now it was not possible for Nitish to win the Muslim support with Modi as PM candidate of NDA. That was the reason why Nitish was never comfortable with ‘Modi for PM' chorus that was getting louder day by day among the rank and file of the BJP. An ambitious Nitish decided to assert himself as he thought that he could afford to part ways with BJP.
The basic assumption behind this line of thought was Nitish Kumar's belief that upper castes, who are largely with BJP, will have no other option because they can't afford a comeback of Lalu who had hostile relations with that community. He was also under impression that even if upper caste voters desert him , the loss will be compensated by the Muslim support that he will get after he dumps the BJP that is anathema to the Muslims.
But both his assumptions have proved to be wrong in Maharajganj. The major chunk of upper castes either did not vote for him or remained indifferent and the Muslims refused to play ball with Nitish despite his high-decibel opposition to Narendra Modi and the outcome was a loss of face for Nitish in this prestigious battle.