Can't roll a leader when he's high in the polls?

Conventional political wisdom says Brash must survive until the polls turn against National. So too does his former chief of staff, Richard Long, who today said you never change leaders when you're ahead in the polls.

But this only makes sense if you assume that supporters will depart the party in greater numbers than those that might join following a change at the top. Maybe true most of the time, but Brash's leadership has rarely been secure and, this far out from the election, the polls can and will change.

I don't accept the lines coming out of National's various back channels, it's not conventional wisdom saving Brash, it's the inability of caucus to agree a successor. Long must know this in which case he's either trying to buy the National caucus some time or he's trying to encourage Brash to leave before he's inevitably pushed.