He's famous for wearing black, but don't be surprised to see Jonah Lomu wearing National blue.

The rugby legend has endorsed Prime Minister John Key on Twitter.

"Great to have a Leader that leads proud to be Kiwi @johnkeypm," Lomu tweeted to his 46,000 followers yesterday.

The backing was promptly re-tweeted from Key's account to its 113,000 followers, with the National leader also tweeting: "Thanks for your support @JONAHTALILOMU. #AllBlackLegend #TeamKey."

Great to have a Leader that leads proud to be Kiwi @johnkeypm pic.twitter.com/hPMx2JCSek

The conversation was not all smiles and joy, with some Twitter users cynical about the sportsman's choice of candidate.

"Yeah a pm who endorses and supports his ministers spending up on alcohol at taxpayers expense," tweeted Andrew Riddell.

Yesterday's tweet was not Lomu's first in support of the National Party - in June, he shared one of the Prime Minister's photos.

"It's great to get support from someone with his mana," Mr Key said last night.

A visit by the Prime Minister to Samoa, Tonga and Niue in June illustrated early in the election campaign that the National Party was keen to get the Pacific community's vote, and Lomu is not the first rugby player to endorse Mr Key.

Former All Blacks Michael Jones and Va'aiga Tuigamala backed the party during the 2008 election campaign.

This year, the Prime Minister starred on the cover of Rugby News magazine wearing an All Blacks jersey with the headline "Pack leader".

Veteran sports commentator Keith Quinn tweeted his disapproval of the move: "On the AB tour of France in 1977 Gary Seear gave me his AB tie. I thanked him but have never worn it. I do not qualify. Err, John Key does?"