A former Green Party leadership contender, Vernon Tava, is seeking the National Party nomination in the Northcote byelection.
He confirmed speculation today that he is putting his hand in the ring but said he could not comment further.
He would not say when he joined National.
Tava stood for the Greens co-leadership in 2015, when incumbent and Climate Change Minister James Shaw won.
Tava also stood as the Green Party candidate in Northcote in 2011 and is a frequent political commentator, including on www.nzherald.co.nz and on Newstalk ZB.
The date for the byelection is yet to be set but it is likely to be in late May or early June.
It follows the resignation announcement of National MP and former Health Minister Jonathan Coleman who has accepted a job to head the Acurity Health Group.
Coleman is a doctor and was first elected to Parliament in 2005.
Tava was considered a moderate in the Green Party and when he stood for the leadership, arguing that the party should able to work across the political spectrum.
Nominations for National close on April 3 and the selection will be held on April 15, the day of Coleman's resignation.
Labour's nominations close on April 10.
President Nigel Howarth said Labour would not repeat National's example in the Mt Albert byelection a year ago, when it failed to take part.
"Even though Northcote is a safe National seat, we are not chickening out like National did at the Mt Albert by-election last year. "
Coleman won the seat at last year's general election, 6210 votes ahead of Labour's Shanan Halbert.