Long-serving Green Party MP Gareth Hughes is retiring from national politics.

The 38-year-old assumed office in 2010 and has been in Parliament longer than any of his colleagues.

Greens co-leader James Shaw wished Hughes all the best

Hughes had been a leading member of the Greens caucus for a decade, Shaw said.

"We will miss him after he retires from Parliament next year. Gareth, I wish you all the very best," Shaw said on Twitter.

Hughes told Stuff he wouldn't seek re-election in 2020 and that the current Government had not been "transformational".

However, NZ Herald political editor Audrey Young told Andrew Dickens that it is not too severe of a criticism 

"He's a hell of a nice guy, but I think he's leaving politics before he was pushed. I think he was due to be sliding down the Greens list next year."