The National Party's most senior adviser, Wayne Eagleson, has quit the job.
Mr Eagleson is Bill English's most trusted lieutenant and has been chief of staff in the National Government for nine years - he was also Sir John Key's right-hand man.
Newshub has learned that Mr Eagleson told Beehive staffers of his resignation today, but will stay on for the next few weeks and play a key role as Government is formed.
That would leave Mr Eagleson able to be involved in talks with Winston Peters, be it formally or just using his political know-how in the background.
Mr Eagleson stayed on in the role after Sir John left and it is likely that he just wants to have a breather and do something new and let some fresh legs get on the political paddock.
It is understood that Mr Eagleson, a National loyalist, had considered quitting when Sir John left, but stayed on after a personal request from Bill English, who is a good friend.
Mr Eagleson is renowned political operative with huge mana in the Parliamentary precinct, as much of National's success can be put down to his greasing of the political wheels.
As chief of staff Mr Eagleson holds a rare political power, once summed up by John Key as "when my chief of staff speaks, it is like I am speaking".
Mr Eagleson followed Helen Clark's chief-of-staff Heather Simpson into the role, who was known as "H2" because she was so close.