TORONTO - With chanting and plenty of orange fashion statements, thousands of NDP delegates descended upon the Metro Toronto Convention Centre Friday to pick the party's new leader -- and the nation's next Opposition leader.

At stake is the party's political future following the historic election last May, which saw the NDP sweep through Quebec and assume Official Opposition status for the first time.

Some candidates are pledging to move the party toward the centre and co-operate with other parties, while others are promising to remain committed to the NDP's founding principles of social justice and equality.

But before the crucial first ballots could be counted on Friday evening, the seven candidates were given 20 minutes each to make their final pitches to the party faithful.

Among that first faction pushing the party's base are Thomas Mulcair and Nathan Cullen, who want to become the next government by expanding the popular vote.

"We have to reach out beyond our traditional base and rally progressives of all stripes behind the NDP banner," said Mulcair, a Quebec MP who is considered the man to beat.

Though Mulcair is the perceived front-runner, he has come under fire from some in the party for saying the NDP needs to "modernize" and ditch some of its socialist roots.

Cullen, a British Columbia MP, is also facing criticism for his controversial call to run joint candidates with the Liberals and Greens to prevent vote splitting in Conservative-held ridings.

Still, Cullen has enjoyed momentum heading into this weekend's vote and is considered a dark horse candidate.

"We should never be afraid of ideas," said Cullen about the controversy, adding that all "progressives" should unite against Stephen Harper's Conservatives.

"Will we seize that opportunity?" he asked.

Responding to that challenge, however, was one of the party's traditional candidates, Paul Dewar, who cautioned against too much co-operation with other parties during his speech.

Instead, he said that the party should continue the legacy left by Jack Layton, who wanted to be a voice of social activism that can speak for working Canadian families.

"We may have lost Jack, but we must not lose our way," said Dewar, who represents an Ottawa riding, but is seen to have weaker French skills than some of the other candidates.

While Layton was picked as leader during the party's last convention in 2003, never before has the NDP faced the proposition of forming the next government.

Delegates from across the country are facing that reality this weekend, meaning the enormity of their choice could have drastic implications for both the party and the political landscape in Canada.

Brian Topp, a former party backroom strategist and the only candidate without a seat in Parliament, has preached social justice over the seven-month campaign.

And it was a message that he repeated on Friday.

"Hear this well. I'm a proud New Democrat and an unapologetic social democrat," Topp said, standing in front of a throng of his supporters.

"Jack Layton won on honesty, openness and conviction, and so will we."

Indeed, Layton's legacy has loomed large over the proceedings, with each candidate offering tribute to the late leader.

Though Topp was the first to declare his candidacy and was a member of Layton's inner circle, he has come up against stiff competition over the past few months.

Toronto MP Peggy Nash is also considered to be one of the candidates positioned toward the party's traditional socialist base.

A former union negotiator, Nash was keen to talk about her record of pushing for benefits for same-sex couples with the Canadian Auto Workers.

Earlier, Nash was greeted by a boisterous group of hometown supporters, who launched into an impromptu dance session as a throng of media watched.

Two other candidates could face a tough battle to live past the first ballot.

Niki Ashton, the youngest candidate at 29, said that she would spark an NDP renaissance in the West that would sweep the party to power.

The Manitoba MP said that Harper takes the West for granted, and she said that he should enjoy being prime minister "while it lasts."

And Martin Singh, a trained pharmacist from Nova Scotia, has been accused of tacitly supporting Mulcair. He was also fined by the party for calling Topp a liar.

Reaction to the speeches

Mulcair's drawn-out entrance into the convention centre, accompanied by a drumming band, was widely panned by political commentators.

Robin Sears of PR firm Navigator told Power Play Mulcair should not have wasted "12 minutes drumming," which forced him to rush through his speech once he eventually made it to the stage.

"He rushed through that speech as if it were a list of side effects in a drug ad," said communications specialist Allan Bonner. "He was not connecting with the audience, he was reading much of the time … it was really a shame not to see Mulcair at his best."

The pundits seemed to favour candidate Cullen's pitch, giving him points for delivering a passionate speech that resonated with the audience.

After the speeches finished up at 5:30 p.m. Friday, the party faithful began voting for the first ballot. The ballot will close at 9 a.m. on Saturday, with results expected an hour later.

At that point, if any candidate wins more than 50 per cent, a winner will be declared.

If not, another vote will be needed, with the lowest performing candidate left off the next ballot.

NDP MP Pat Martin told that he's expecting three ballots for the winner to be declared.

While the NDP has been accused of running a low-key leadership race, former leader Ed Broadbent caused a stir when he declared that Mulcair wouldn't be a good choice because of his temper and his desire to push the party to the centre.

But on Friday, Broadbent dismissed the suggestion that the party will be doomed if delegates choose "the wrong candidate" who is not ready to take on Harper and the Conservatives.

Broadbent said political leaders always "grow into" the top position as they gain experience.

"I don't think it's an all-or-nothing contest at all," he told Power Play.