For the Gandhi Congress, this energy is not I think a battle for revival, it is a battle for survival. They are not looking to win, they are simply trying to look like a credible opposition. For even along that limited axis, they seemed to have been failing earlier.
It was a typically impressive Modi performance, mingling mythological references (Karna's gloomy charioteer in the Mahabharata) with robust defences of his record in office, repositioning of himself as an "outsider", and, of course, the usual trenchant attacks on the Congress.
Now that growth has naturally slowed, as was inevitable, given the policy choices that Modi made, how will he balance these narratives? Can he afford to lose those middle-class voters who might actually conclude that he has done a bad job with the economy?
It's a constant puzzle to me that so many of the critics of the Narendra Modi government - including, in fact led by, the Congress party - want to blame it for some of the few things it does right on the economy. The current attack on the government's pricing policy for petroleum products such as petrol is Exhibit A here as far as I'm concerned.
Of course, it is pure coincidence that Kumar's JD(U) and the BJP together have a majority of one in the Bihar Assembly. Such things as arithmetic can have no bearing on Kumar's decisions, only his conscience does.
Only two people know the reasoning behind decisions taken by the Bharatiya Janata Party: Narendra Modi and Amit Shah. Venkaiah Naidu may have wanted the job, but that's not usually an asset in Modi's eyes, or Shah's. So what else could have set him apart from the pack?