The Labour Party hopes special votes will tip the marginal west Auckland seat of Waitakere into its hands.
Incumbent National MP Paula Bennett led Labour's Carmel Sepuloni by 349 votes on election night.
But Labour's Auckland regional chair Greg Presland says Waitakere is still up for grabs with more than 3400 special votes yet to be counted.
He says Labour's Lynne Pillay won 200 more special votes than Ms Bennett in 2008.
Mr Presland says there are more special votes this time and Waitakere could go right to the edge if they are divided in similar proportions.
For preliminary results in all seats go to Radio New Zealand's Electorates page.