Burnaby South NDP MP Kennedy Stewart has confirmed he'll run for mayor of Vancouver as an independent, with the aim of uniting the city's left-wing parties.

The two-term MP said he would be resigning his seat in parliament on Thursday in order to campaign.

"Progressive forces need to come together to keep the NPA out of power," Stewart said at a news conference in Vancouver on Thursday morning.

That means Stewart will be effectively running against Shauna Sylvester, who announced similar plans to unite the centre-left as an independent.

The centre-left parties — Vision Vancouver, the Greens and COPE — have yet to nominate any official party candidates for mayor.

Glen Chernen, John Coupar and Ken Sim are running for the NPA nomination.

Stewart, 51, was most recently in the news for being arrested alongside federal Green Party Leader Elizabeth May after protesting the Trans Mountain pipeline expansion at Kinder Morgan's tank farm on Burnaby Mountain.

The province appointed a special prosecutor to handle the case.

Stewart, who has a PhD from the London School of Economics, is also currently on leave as a professor at Simon Fraser University's School of Public Policy.

He was first elected to the House of Commons in 2011.