Do you know the politics of Bihar and plans of BJP?
Currently when the politics of JDU and nitish kumar is at an end, the top leadership of bjp would not want that Tejashwi Yadav, who is rapidly increasing his stature in the state politics, should get the benefit of Nitish Kumar's political legacy in the future. bjp also wants to have its own chief minister in bihar and to be in power on its own in the state. This can be possible only when there is a direct contest between bjp and RJD in bihar and Nitish is not in such a condition that the government cannot be formed without him. This will happen only when JDU's political land becomes smaller and that land is not occupied by RJD.
Meanwhile the top leadership of bjp is moving forward keeping this aspect in mind. Coming together with Nitish will not only directly benefit bjp in the lok sabha elections, it will also help in getting into a position in the future Legislative assembly elections, from which bjp can make its chief minister without any conditions.
Moreover if Nitish remains with bjp and continues to juggle with bjp in the upcoming assembly elections, it will help in stopping RJD in the lok sabha as well as assembly elections in future. Nitish Kumar's popularity is decreasing rapidly. The support base of his party is no longer such that there is a strong possibility that Nitish will be able to get his point across in the upcoming assembly elections.