The gap between National and the centre left block of Labour and the Greens has tightened in the wake of John Key's departure as leader, according to the first major poll since his shock resignation.

National is at 46 per cent in the first 1 NEWS Colmar Brunton poll for the 2017 election year, down four points from the November poll.

Labour has climbed two points to 30, while the Greens are steady on 11 per cent, taking the centre left block's combined vote to 41 percent.

That narrows the gap between National and the centre left pairing to just five percent.

Back in November National was 11 per cent ahead of the Labour-Greens combo.

New Zealand First is up one per cent to 11, and, based on our polling, would hold the balance of power post-election.

ACT is up one to one per cent, as is the Mana Party, which is back in the frame on one.

The Maori Party is steady on one per cent.

BILL ENGLISH POLLS WELL

In the preferred Prime Minister rankings, Bill English comes straight in at 31 per cent - just five points shy of where John Key was in November.

Mr Key has slipped back to two percent.

Labour leader Andrew Little is down one point to seven per cent, behind Winston Peters who is steady on eight per cent.

Labour MP Jacinda Ardern, who is contesting the Mount Albert by-election on February 25, is on four percent.

While this first 1 NEWS Colmar Brunton poll shows the gap closing between National and the centre Left to just five points, National's strategists will be pleased with the party’s showing, given the risks of the change from the popular John Key to the more laid back Bill English.

Remember, when Bill English was last leader of the National Party in 2002, he took them to their worst election defeat.

Likewise, Labour will be encouraged that their party vote has climbed to the psychologically important 30 per cent mark, which doesn't seem to have come at the expense of their Greens coalition partner.

However, Andrew Little's poor showing in the preferred Prime Minister stakes remains a worry as September's election draws closer.

The poll of just over 1000 eligible voters was taken between February 11 and 15.