Nikhil Mandal had contested the 2020 assembly polls from Madhepura but lost to RJD.
JD(U) spokesperson Nikhil Mandal on Monday resigned from the post he had been holding for more than six years citing "personal reasons".
Former ally BJP, which has been licking its wounds since losing power in Bihar, claimed that the development cited "discomfort" of JD(U) spokespersons in defending Chief Minister Nitish Kumar, their de facto leader.
Nikhil Mandal (41), among the youngest spokespersons of the party, announced his resignation on Twitter.
He also shared a screenshot of the communication he sent to the party leadership on his official letter head.
In his letter which is addressed to no one in particular, Nikhil Mandal has said, "I am resigning from the post of JD(U) state spokesman. I am thankful to you all for having assigned this post to me since 31.01.2016. Please accept my resignation."
The party's chief spokesperson and MLC Neeraj Kumar, when asked about the development, said "had he resigned because of political reasons I could have said something. But since the reasons have been stated to be personal, it would not be proper to comment".
Meanwhile, state BJP spokesman Nikhil Anand issued a statement wondering whether JD(U) spokespersons were "in a state of discomfort having to defend the Mahagathbandhan which has the RJD as its ally".
Notably, Nikhil Mandal had contested the 2020 assembly polls from Madhepura but lost to RJD veteran Chandrashekhar, the minister for education in the new government.
Nikhil Anand also sought to underscore that before the exit of Nikhil Mandal, JD(U) had removed two other spokespersons, Suheli Mehta and Ajay Alok, for their perceived proximity to disgraced former national president RCP Singh.
Suheli Mehta continues to be in the party, while Ajay Alok, incidentally seen on the same page as BJP on a number of issues, has been expelled.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)