Voters appear to be deserting the Labour Party for the Greens as Phil Goff's election chances look increasingly hopeless.

The Greens have leapt to 11 per cent in today's Fairfax Media-Research International Poll – and their rise has come at the expense of Labour, which has slumped to 25.7 per cent.

With 86 days until the election, there are echoes of 2002 in the latest poll results.

RUSSEL NORMAN: Green swing for the right reasons.

That year National crashed to a disastrous 20.9 per cent vote on election night, with supporters panicked into voting strategically for the minor parties, particularly NZ First, after deciding Bill English had no hope of victory.

The Green Party's improved result in this poll shows the party may be benefiting from a shift in its position towards National. It had previously ruled out working with National in any sort of coalition deal.

The Greens now say that although a deal with National is "highly unlikely", they will not shut the door completely. But yesterday Green Party co-leader Russel Norman dismissed suggestions of tactical voting on the Left.

"Under MMP every vote counts ... people are feeling that they are voting for the Greens in a positive way."

Labour has been dogged by continuing leadership speculation and caucus ructions over leaks suggesting that Mr Goff had consulted his front bench over whether or not to quit.

Yesterday one-time leadership contender Shane Jones appeared to point the finger at supporters of finance spokesman David Cunliffe, who is shaping up as Mr Goff's biggest rival. Mr Goff insisted yesterday that people who continued to question his leadership were "flogging a dead horse".

He denies that he has raised his leadership as an issue.

In today's poll, the second in the series, Labour's support is down three points, and National's support is up only marginally, from 56.1 per cent to 57.1 per cent.

But the number of undecided voters is up – from 12.1 per cent a month ago to 16.2 per cent. National would comfortably govern alone, while Labour would lose several sitting MPs, including rising stars Stuart Nash, Carmel Sepuloni and Kelvin Davis.

Prime Minister John Key remains National's most potent weapon. He towers above Mr Goff in the preferred prime minister stakes, at 54.6 per cent to Mr Goff's 8.5 per cent. Mr Key appears to have cemented his popularity since the previous Fairfax-Research International poll a month ago, with the number of undecided voters down from 29.9 per cent to 22.5 per cent.

Labour now faces a near impossible task of hauling back National's massive lead in a campaign that will probably turn into a referendum on the Government's handling of the economy and a series of disasters including the Christchurch earthquakes, finance company failures and the Pike River disaster. Labour has struggled to get traction while the Government has managed the country through the crises.

The other big shift in today's poll is a drop in support for ACT, which sits at 1.1 per cent – a slap in the face for Don Brash, who promised the minor party a lift in support under his leadership.

Former National Cabinet minister John Banks could end up being ACT's only MP after the November 26 election, assuming he wins Epsom.

The Fairfax Media-Research International poll was conducted on August 25 to 29 and surveyed 1000 eligible voters. It has a margin of error of 3.1 per cent.