But there is no requirement for the largest party to lead the Government. The Government must be formed by parties which between them can command the majority of the seats in Parliament on confidence and supply issues, such as passing the Budget.
While most polls this term have had New Zealand First holding the balance of power and able to put National or Labour into Government, in the last Colmar Brunton poll in which National polled 39 per cent to Labour's 43 per cent, National would not have been able to form a Government alone with New Zealand First.
However, Labour had more options. It would comfortably have been able to form a coalition majority Government with New Zealand First, without needing the Green Party's support. But it would also have been able to form a Government with the Greens and the Maori Party, without New Zealand First.
Last night's Newshub Reid-Research poll put National well in front at 47.3 per cent to Labour's 37.8 per cent. The Kantar TNS poll of 1000 respondents was conducted from August 30 to September 4 and has a margin of error of plus or minus 3.1 per cent. It is an online survey by ConsumerLink which runs on the Fly Buys panel of 120,000 active members, one of the largest in New Zealand. Sampling is nationally representative and is then post-weighted by age, gender and region.