Voters were fed up with "beneficiary bashing" from National MP Paula Bennett when they decided not to return her to her Waitakere seat, Labour's Carmel Sepuloni says.
Ms Sepuloni was declared the winner in the seat on Saturday, when the final election results showed her beating Ms Bennett by just 11 votes.
National will seek a recount because of the close margin.
Ms Sepuloni told the Sunday Star Times Ms Bennett - who entered parliament after winning the seat in 2008 - has not been good for Waitakere.
"Despite the fact it is close, it just goes to show that there are 11 more people that think she wasn't [good]," Ms Sepuloni says.
Ms Bennett's hardline stance on welfare as minister of social development doesn't appeal to the high numbers of sole-parent households in the west Auckland electorate, she says.
"On the doorsteps, at the malls and supermarkets, when we talked to people [they said] they were struggling with the bare necessities ... whether it be putting food on the table or maintaining a roof over their head."
The loss was part of a double blow for National in the election results - with the special votes taking away another seat and giving it to the Greens.
That means the Greens will get a fourteenth MP in Mojo Mathers, who will be the country's first deaf MP.
However, National picked up another seat on Saturday, with Nicky Wagner taking Christchurch Central off Labour's Brendon Burns by 45 votes.
He's asked for a judicial recount.
The National-led government still has the numbers it needs to govern the 121-seat parliament, with 61 votes including two from ACT and United Future.
Prime Minister John Key is hopeful of adding the three Maori Party MPs to that line-up, with a deal expected to be signed on Sunday.
NZN