A political expert says Labour gave Nick Leggett little choice but to jump ship.
LISTEN ABOVE: Newstalk ZB's political editor Barry Soper spoke with Mike Hosking
The former Porirua Mayor is standing for the Mana seat as part of the National Party.
Earlier this year he quit Labour to stand against the party's chosen candidate Justin Lester for the Wellington Mayoralty.
SEE ALSO: Nick Leggett spoke with Larry Williams
Massey University Professor Claire Robinson said Andrew Little has been so vocal about Nick Leggett being disloyal to the party.
"What do you do? You can't hang around waiting to be told or advised when you become loyal again, so actually I think he didn't have much choice but to stand for another party."
She said it's not unusual for candidates to change parties before being elected, but people don't usually find out.
Ms Robinson said a lot of them won't admit they've been members of other parties in earlier life, but Mr Leggett is much more high profile.