Another candidate in the Mt Albert by-election has unmasked himself.

Act list MP John Boscowan has confirmed rumours he will run for the former Prime Minister's seat. He says despite Helen Clark's long tenure in the electorate, the seat is now anyones.

"Helen Clark has obviously been a very loyal and highly regarded MP. She had a huge majority but at the last election the difference between the National Party and the Labour Party was actually very small on the party vote and I think that represents a real opportunity for the Act Party."

The Aotearoa Legalise Cannabis Party is also releasing the name of its candidate this afternoon.

Greens co-leader Russel Norman is standing for his party. Labour selects its candidate tomorrow. Melissa Lee is expected to stand for National.

The by-election will be held on June 13.