United Future leader Peter Dunne is playing down any suggestions his Ōhariu seat is under threat from former Police Association president Greg O'Connor.
Mr O'Connor - the face of the Police Association for 20 years - has thrown his hat in the ring as a Labour Party candidate.
A key strategic seat for the government, Ōhariu is currently held by Mr Dunne, one of National's support partners.
Mr Dunne has held the seat in Wellington's Northwest since 1984, but his winning margins have slimmed down over time - he won by 700 votes in the last election.
The seat was a lifeline for the United Future leader, whose party did not reach the 5 percent threshold in the past four elections.
Mr Dunne told RNZ he was not bothered by his potential new rival.
"He's picked the electorate like some people pick darts on a dart board.
"This is where he might like to stand. He doesn't live there, doesn't have any real connections there, but good on him for giving it a go.
"The last time we regularly had Labour candidates who lived in the place and were part of it, was when I was the Labour MP and that was over 20 years ago."
Prime Minister Bill English said he was surprised by Labour's support for Mr O'Connor.
"Well, it's not consistent with the fresh bright faces for the future, that's for sure," Mr English said.
If Mr O'Connor did not win the seat, Labour leader Andrew Little has signalled he could have a high placing on the party list.
"I'm very keen to have him on my team regardless. I think he'll be an excellent contributer to a Labour caucus after the general election," Mr Little said.
The Green Party has not yet announced who it will stand in the seat.