Act deputy leader John Boscawen says he would be delighted if he won the Tamaki seat, and would postpone his retirement and not force a byelection.
His stance could be interpreted as a change of heart, as Mr Boscawen announced his retirement in September for family reasons and because of the long hours he demanded of himself as an MP. Although he withdrew from the party list, he continues to stand in Tamaki.
Asked how he would react if he won, he said: "Obviously I'd be very pleased to be the MP for Tamaki, and I'd go about the job with as much enthusiasm and hard work as I've shown in the last three years.
"However, my principal reason for standing is to encourage people to give their party vote to Act."
He said he was not asking for the electorate vote. "But if they were to give two ticks to Act, I would have no objection to that at all."
In 2008, National's Allan Peachey had a 17,020 majority. Mr Peachey died almost a fortnight ago.
There may be a tiny opening for Mr Boscawen, as new National candidate Simon O'Connor does not have as high a profile.
Mr Boscawen - who came to nationwide prominence during the 2009 Mt Albert byelection when he continued speaking after an activist placed a lamington on his head - said being an electorate MP would not drag him away from his family, because much of his work would be in Tamaki, where some of them live.
He would also be freer to spend time in the electorate because he would not have ministerial duties; he was formerly the Consumer Affairs and Associate Commerce Minister.
Dr Brash said he would support Mr Boscawen being re-elected, even if it meant denying himself a seat in Parliament.
"It would be fantastic. I'd be delighted if he won Tamaki. He would be absolutely upset, I suspect, because he doesn't want to win Tamaki."
If Act won about 1.5 per cent of the party vote and John Banks won Epsom and Mr Boscawen won Tamaki, Dr Brash - who's first on the party list - would be left out.
"I would certainly be disappointed not to be in there [Parliament]," he said. "But when you contest an election, sometimes you have to accept that you won't win."