Mr Drabu, the state's finance minister, was sacked yesterday, sources said, after his remark that Kashmir is "not a political issue" triggered a huge controversy.
Mr Drabu was the key channel of communication between the PDP and the BJP and was instrumental in helping the alliance survive the rocky patches since it was cobbled out in 2015.
Along with Mufti Mohammad Sayeed, the father of Chief Minister and PDP chief Mehbooba Mufti, the 53-year-old economist had played a pivotal in the crafting of a common agenda for the PDP-BJP alliance in the state.
Since the death of Mr Sayeed in January 2016, Mr Drabu, BJP sources said, helped get across the party's views to PDP and help bridge the huge ideological gap between the two parties that appeared unbridgeable. Be it the Common Minimum Programme or any other governance issue over which the rift had widened, he played a vital role in resolving the issue.
Sources said the top leadership in Delhi is now concerned about whether the PDP would take a hard line in Mr Drabu's absence. The state BJP leaders are expected to help the brass in crafting out a strategy.
Mr Drabu was asked to step down yesterday by Chief Minister Mehbooba Mufti after the party agreed that he had crossed the line with his remark and left it open to attack from both mainstream political parties and separatist groups.
At a function on Friday, Mr Drabu had said: "Those who see Jammu and Kashmir as a conflict state, as a political issue ...it's a society which has social issues right now...It's not a political issue as far as I can see, I think we are barking at the wrong tree for the last 57 years by talking about the politics of it, that the political situation has never improved. We seriously need to look at in terms of how it is a society that is in search for itself."
Critics said the statement was proof of a "political sellout" by the PDP to stay in power.
The PDP has asked Mr Drabu to explain the comment and retract it. The party also said it recognizes Kashmir as a political issue and has been trying to resolve it through dialogue.