The NDP have officially opened their 50th anniversary convention in Vancouver with party leader Jack Layton thanking the volunteers who helped them win their best-ever election result.

Layton said the delegates who gave their time and money have given Canadian families the strongest voice they've ever had in Parliament.

"You are the reason that New Democrats are Canada's Official Opposition – fighting for the values we cherish," Layton said

Canadians elected the NDP to be the Official Opposition, but also to propose ideas, not just to oppose the government, he added.

"It's up to all of us in this room to live up that responsibility – to provide Canadians with a positive alternative and to build a strong and united country. To grow our economy, create new jobs, and always put the needs of everyday families first," Layton said.

Softening constitution

Delegates to the NDP convention are moving toward softening the party's constitution as they sets their sights on the government side of the House of Commons in four years.

A resolution to remove a reference to 'socialism' from the party's constitution has made it through a break-out policy session and will go onto the full plenary session on Saturday, CBC News has learned.

But the resolution narrowly passed in the closed-door workshop session, a source told CBC.

Delegates seemed to be against the preamble and the vote was so close they had to stand up to show how they were voting.

Layton says the party isn't abandoning its roots by trying to change the wording.

"But there's always a debate, and has been for years in the party, about some of the language we use to describe ourselves. And there's been quite an evolution in social democratic thinking and governments and parties around the world, we're talking for half a century here," he told Rosemary Barton on CBC's Power & Politics.

"The delegates will decide on what phrases, what terminology [best] captures what it is that we're offering to Canadians."

The NDP's national director says the idea is to modernize the language of the constitution rather than change the party's values.

"I don't know if many delegates look at it as a left-right issue," Brad Lavigne told Rosemary Barton in Power & Politics' The War Room podcast.

A potentially controversial resolution to ease Canada's marijuana laws didn't make it through the closed-door session, another source told CBC News.

Broadbent announces initiative

At the first open event of the day, Ed Broadbent, who had been the party's most successful leader until Jack Layton led it to a historic seat count, announced the creation of a left-leaning think tank.

Broadbent said the independent think tank would reach out to social democrat-leaning academics for their ideas, provide education and train activists.

"I have for some time thought we should have something like this," Broadbent said. "Our founder [Tommy Douglas] well understood a political movement or idea doesn't live in the past."

It's not clear how the institute will be funded, although Broadbent said it will operate as an NGO.

The convention marks the party's 50th anniversary, which officials say is an opportunity to look back and look ahead to how they campaign to be Canada's next government.

A lot of people are thinking the party needs to be more mainstream, CBC's Laurie Graham reported from the convention.

"The NDP are in a mood to celebrate," Graham said. "Not only because of their success in the last election."

"One of the things they'll do is a retrospective and look back, and [party founder] Tommy Douglas will be highlighted," she said.

The NDP won Official Opposition status in the May 2 election, taking 103 seats in the House of Commons.

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