I reckon that if Labour and the Greens combined get more votes than National next election, they’ll be able to find enough support parties to govern. Vice versa too.
During the last term, National averaged an 11% lead over Lab+Green. This term 3%. Since June, less than 1%.
Until March, Lab+Green had been less then National for over four years. Since then, it has been equal or above half the time. In both August polls, Lab+Green was ahead.