Canadian Labour Congress president Hassan Yussuff says Tom Mulcair does not deserve another term as NDP Leader and predicts he will win less than 60 per cent in Sunday's leadership review vote.

"I have told Tom that. I met Tom and had dinner with him, and I basically told him I don't have an argument as to why you should remain as leader of the party, much less leading the party in terms of the 2019 election," Mr. Yussuff told The Globe and Mail.

The CLC leader, whose organization represents 3.3 million workers, said Mr. Mulcair must be held responsible for allowing the Liberals to outflank the New Democrats with more progressive policies in last year's election. He said he does not believe Mr. Mulcair has the personality or ideological makeup to challenge the much younger and left-leaning Prime Minister Justin Trudeau.

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"Some union leaders, of course, have said they would like him to stay. Some want to see a review in 2018. The fact is the party is at 11 per cent in the polls, we lost the largest number of seats under Tom's leadership and we lost the opportunity to form government," he said. "This was the best moment we had to form a national government and we lost it."

Mr. Yussuff said he has had wide-ranging discussions with NDP grassroots activists across the country and he is hearing a lot of ridings are divided, with many members disillusioned about the NDP Leader. Even among Mr. Mulcair's supporters, there is little enthusiasm, he said.

"Maybe he'll get 50 per cent, but the bigger question is how much more than 50 per cent does he get," Mr. Yussuff said. "I think he has to get 60-per-cent-plus to hold on to his leadership."

Mr. Yussuff acknowledges five union leaders representing Unifor, the United Steelworkers, the International Association of Machinists and Aerospace Workers, United Food and Commercial Workers and the Canadian Union of Public Employees believe the NDP Leader should have another chance to prove himself – until at least the next leadership review in 2018.

The Globe called riding associations across the country and found many members are divided and unsure about giving Mr. Mulcair another chance.

"I think it's 50-50 when I talk to people," said Ed Stecewicz, the riding president for Timmins-James Bay, which is held by NDP Charlie Angus. "Some people are saying Tom doesn't seem to be the builder that we need. Some people are saying there is another leadership review in two years, so let's put him on probation."

James Kosowan, chief executive officer of the Edmonton Strathcona riding association, says the 33 delegates attending the convention are split. The riding is the home to Alberta's only NDP MP, Linda Duncan, and many in Alberta expected more New Democrats to win.

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"There's people on both sides. I'm hearing some that are very supportive, some that don't want a leadership race right now and so on. And others that think it's time for a renewal, and there were mistakes that were made during the election and these need to be addressed, and maybe that means new leadership," he said.

Mr. Kosowan said he will make up his mind when he hears from Mr. Mulcair at the convention.

"I'm kind of on the fence," he said.

All three delegates in Toronto's York South-Weston riding, which was held by the NDP's Mike Sullivan until he was defeated in the election, are voting against Mr. Mulcair. "There is still a lot of anger and a lot of concern. I would say all of our delegates will not be voting to support Mr. Mulcair," said a riding official who asked not to be named.

Gord Landriault, financial agent of the Churchill-Keewatinook Aski riding association in Manitoba, is undecided and waiting to hear Mr. Mulcair's plans for rebuilding the party. Mr. Landriault, who also works for MP Niki Ashton, said he would support his boss if she ran for the leadership.

"If there is a challenge and she decides to run, she's got my support. That's up to the convention to decide," he said.

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Gilles Demers of the Rimouski-Neigette-Témiscouata-Les Basques riding association, home to Quebec MP Guy Caron, says he and another delegate are supporting Mr. Mulcair.

"The feeling in Quebec, more or less, is that if we want to change the leader, we have to find [a] candidate," he said. "And up to now, it's not clear from the Quebec side we'll have another candidate who can challenge Thomas Mulcair."

Nicholas Stein, the riding president in Windsor West, which is represented by veteran NDP MP Brian Masse, said there is "no groundswell of opposition" to Mr. Mulcair in his area and he is confident all the delegates will support the leader.

The convention is much more popular than anticipated: Party officials expected about 800 people to sign up. Now, 1,500 delegates are going.

National director Karl Bélanger says it is a sign that people are interested in the future of the NDP.

"It's very good news for the party that people are engaged and looking forward to debate the path forward," he said. "It is beyond our expectations and so we're quite happy about that."