Manukau Mayor Len Brown has a slender lead over Auckland City Mayor John Banks, but the race for the Super City mayoralty is too close to call.

A day before voting papers start going out for the Super City elections on October 9, a Herald-DigiPoll survey shows Mr Brown with 29.8 per cent support, only two percentage points ahead of Mr Banks on 27.8.

The gap is within the 3.6 per cent margin of error, and both men are behind "undecided" - the choice of 35.2 per cent of the 750 people polled.

The figures have barely changed from last month's poll, which showed Mr Brown on 29.6 per cent and Mr Banks on 28.7 per cent.

Pollster Dr Gabriel Dekel said a trend since early polls of Mr Banks gaining ground, if combined with a low voter turnout among ethnic groups and low-income people who supported Mr Brown, could result in a Banks victory.

The survey found support for the minor contenders has fallen to below the margin of error since last month's poll.

North Shore Mayor Andrew Williams has dropped from 3.9 per cent to 1, and businessman Colin Craig is down from 3.5 to 1.9.

Last night, Mr Brown said he had been ahead in all the polls this year, but that was irrelevant as postal voting was about to start.

"I'm out there doing everything I can to connect with the community and give them a positive vision for Auckland's future," he said.

Mr Banks said Aucklanders had to consider who was the best leader to make the tough decisions when they were needed most - and vote.

"It's a very hard-fought battle for the hearts and minds. On election day, it will be very close," he said.

One poll question found Mr Banks would be the best mayoral candidate in a crisis like the Christchurch earthquake, but another found that Aucklanders appear to be taking a shine to Christchurch Mayor Bob Parker, who has won praise for his handling of this month's quake in the Garden City.

The poll gave Mr Banks 27.9 per cent support as the leader for a crisis, comfortably ahead of Mr Brown, who was on 19.2.

But the two local mayors could face serious competition in the crisis stakes if Mr Parker were to enter the Super City mayoralty.

Asked if they would rather vote for Mr Parker if he stood as a mayoral candidate in Auckland, 36.2 per cent of those polled said yes and 43.6 per cent said no.

Mr Parker said he was "incredibly humbled" by the survey result.

"Right now I'm probably in the middle of a bit of sleep deprivation, and it's just the kind of boost that I need. I must say it's a generous thought."

He's not in any great hurry to seek Super City glory.

But he joked: "If I don't have a job by the end of the [election] in Christchurch, if they wouldn't mind delaying the election up there for a week or two, I might be happy".

- ADDITIONAL REPORTING: JARROD BOOKER

TONIGHT
Watch the Herald mayoral debate live on nzherald.co.nz

Readers can send in their own questions for candidates to nzherald.co.nz here or via the nzhdebate Twitter account.