Labour has launched an attack on John Banks' management of Auckland City finances during his time as mayor as it seeks to derail his bid to retain Act's hold on the key seat of Epsom.
Both Mr Banks and Labour candidate David Parker yesterday said the outcome of the November 26 election could turn on the result in Epsom.
Recent polling, including Act's own internal research, puts National's candidate, Paul Goldsmith, ahead of Mr Banks in spite of the implicit message to National voters that they should give their electorate vote to Act's man.
Should Mr Banks fail to hold Epsom for Act, the party looks almost certain to lose its presence in Parliament, depriving Prime Minister John Key and his government of the support of five MPs to their right.
Sensing blood in the water, Labour has stepped up its attacks on Mr Banks, which have included leaflets highlighting some of the former Cabinet minister's past statements, including racially charged comments and his unfavourable views on homosexuality.
On Saturday, National-friendly blogsite Kiwiblog ran a guest post from Mr Parker in which he highlighted the recent poll numbers and criticised Mr Banks' record in managing Auckland City's finances.
"Few people knew that John Banks tripled Auckland City Council's debt during his last three years as Mayor," Mr Parker wrote.
"This recent history is very damaging for Key as well as Banks, given their repeated assertions that they are fiscally responsible and Labour is profligate."
Mr Parker claimed Auckland City's debt rose from $135 million to $738 million during his Act rival's last term as mayor. The Herald has reported that debt rose from $322 million to $867 million over the same period.
Mr Banks would not comment on Mr Parker's attack on his fiscal management, but said he was prepared to debate the issue with him. "If he wants to raise it at public meetings, let that be so."
Mr Banks also refused to comment on the leaflets, one of which presented a derogatory comment he made about Pacific Islanders in 1978 as if it were made last year.
Yesterday, Mr Parker said he had nothing to do with the pamphlet, but he believed it was fair for Mr Banks to be held accountable for the comments now as they were "part of his political life".
A National Business Review/UMR poll released on Friday showed that Mr Banks was on 24 per cent against Mr Goldsmith's 37 per cent. However, the poll suggested Mr Banks would win if he received an explicit endorsement from Mr Key.
But yesterday, Mr Banks said he was "not asking for any favours from the Prime Minister or the National Party".
"I'm going out to win the hearts and minds of the people of Epsom.
"Three years ago, National was 55 per cent in the polls and on election night were 45 per cent of the vote and if that's replicated again then it's critical that Act are well represented in the next Parliament and that is what we've got to convince the people of Epsom of.
"What they clearly don't want is the politics of [Labour leader] Phil Goff and his coalition of losers - everyone that would follow Phil Goff into Government given the opportunity."