Labour Leader David Cunliffe says support for the National Government will "corrode" over coming months as public discomfort over perceptions of crony capitalism such as the Oravida affair grows.

Front footing a disappointing Herald-Digipoll result this morning which showed support for National rising five points to 50.8 per cent Mr Cunliffe said Prime Minister John Key and his party were benefiting from being in power for some time and "a temporary upswing in the economy as a result of high dairy prices and an quake insurance payments.

National showed no sign of being affected by allegations of a conflict of interest that engulfed high flying minister Judith Collins around dairy export company and financial supporter of the National Party Oravida which gained momentum during the polling period.

Read more of today's Herald-DigiPoll coverage:
National, Greens up, Labour at new low
John Armstrong: Labour's best hope for Key to hit political banana skin pre-election


However, Mr Cunliffe said he expected that would "filter through" and affect National over time.

"And as it's part of a broader narrative about National and crony capitalism I think National will corrode because New Zealanders do not like the idea that Government ministers are using their position to enrich themselves, their party and their family."

Mr Cunliffe said the poll, which had Labour slipping below the 30 per cent mark, showed "we've got more work to do".

Referring to questions around his use of a trust to receive donations to support his leadership campaign last year, Mr Cunliffe said: "We expected to take a hit, we did and now we're moving on".

"It reflects a particular point in time that's already behind us. We're in a new phase now announcing new policy around our economic direction with an important speech on forestry tomorrow and I think you'll seen in more detail where we're headed."
Mr Cunliffe also expressed some doubt over the accuracy of the poll.

"Our internal polls show us unmoved in the mid- 30s."

Deputy Prime Minister Bill English said the result was "just another poll".

"There's a lot of work to do around people's expectations of what the economic recovery is going to do for them."

Mr English said while it was good to see the poll's finding that more New Zealanders thought the Government was moving in the right direction, "they will want to see an economy that delivers more jobs and higher incomes".

"This is a Government particularly under the leadership of John Key that's not complacent about that at all. In fact there's some real risks at this stage in the cycle. For instance as interest rates inevitably rise you start getting what you getting from the Opposition which is the idea that somehow we should go on some spending spree, that we should let inflation run out of hand, all these things would make the recovery less sustainable and deliver less to New Zealanders."