The war of words in Waitakere is raging on, with Cabinet minister Paula Bennett accusing Labour of "nasty rhetoric" for suggesting her loss in the seat is due to National's welfare reforms.

And the exchanges between Ms Bennett and Labour's Carmel Sepuloni could continue for another round, as they await a judicial recount.

Saturday's official election result saw Ms Sepuloni defeat Ms Bennett by just 11 votes, after the preliminary result handed Ms Bennett victory.

It is a blow to Ms Bennett and the National Party to lose a seat that has previously been a Labour stronghold.

However, Ms Bennett will remain an MP due to her high list placing.

It is uncommon for incumbent MPs to be voted out when support for their party is on the rise. National won the electorate party vote by 957.

It is also uncommon for a newcomer to the electorate to defeat an incumbent on their first attempt.

Ms Sepuloni said yesterday there had been a voter backlash over Ms Bennett's "beneficiary bashing".

"I know a lot of sole parents in West Auckland have not been happy with things like the cuts to the training incentive allowance and the constant beneficiary bashing that has come from the National Government, including the Minister of Social Development."

But Ms Bennett, through a spokeswoman, hit back.

"That's exactly the kind of nasty rhetoric we saw from Labour in Waitakere all through the campaign," the spokeswoman said.

"More than 13,400 people clearly support Paula Bennett because they voted for her to be their MP so with a difference of just 11 votes, they deserve a recount, not a tirade of abuse from Carmel Sepuloni."

The result means National's Aaron Gilmore loses his seat in Parliament.

A recount is also expected for the Christchurch Central seat, where National's Nicky Wagner beat Labour MP Brendon Burns by 45 votes.