Severed ties between the Canadian Labour Congress and Unifor have culminated in the head of the national lobby group for the labour movement accusing Canada's largest private sector union of raiding another union for members.

Unifor's president says the union's decision to leave the CLC this week was due to concerns including what it says are some U.S.-based unions stifling workers' rights to change the group representing them. The head of the CLC retorts that Unifor left so it could lure members away from other unions to boost its own membership, a move that is forbidden under the CLC's constitution.

Just one day after Unifor announced it was leaving the CLC, Unite Here Local 75, which represents hundreds of hotel workers in Toronto and Mississauga, Ont., announced it was seeking to leave its U.S.-based parent union and join Unifor.

"Since the disaffiliation, they are now involved in raiding Unite Here in Toronto," CLC president Hassan Yussuff said.

"If you leave the congress, then, of course, you're free to go and solicit any members that they wish to join their union. And that's what they're doing right now."

Unifor president Jerry Dias insisted leaving CLC is not about boosting its membership.

"I have zero interest in raiding any unions. We will respond to those that attempt to raid us, but this has absolutely nothing to do with raiding," he said.

The infighting has left some inside the movement scratching their heads over who is to blame and others asking why they are blaming each other at all, given the challenges the entire movement faces, including an overall decline in unionization rates.

"There's some elements of truth on all sides," said Stephanie Ross, an associate professor at McMaster University's School of Labour Studies.

However, she added, there are many critics within the movement of the CLC's difficult process to make a change in union representation, and it would be in the movement's best interest to re-examine its process.

"Because a disunified labour movement is a serious problem."

Unifor has recently struggled to expand its membership by attracting new workers, said Ross, pointing to a recent failed effort with some Toyota workers in Ontario.

There's likely some internal frustration that the union is unable to recoup the members they're losing due to factors such as job losses through new union drives, she said. But whether that is a factor in their decision remains to be seen, she said.

Dias said the CLC rules that give disgruntled unionized workers an avenue to choose different representation don't work, particularly because U.S.-based unions that are also part of the CLC don't want them to be effective.

Among the CLC's 65 members, there are 33 international unions. The Air Line Pilots Association International, for example, is an affiliate that represents pilots at airlines in both the U.S. and Canada.

While unionization rates have fallen drastically over the past two decades in Canada, the drop in the United States has been even larger.

For U.S. organizations, there's financial incentive to keep Canadians in their unions, said Dias, considering 28 states have so-called right-to-work laws that make union dues unenforceable.

"Canada is a major cash cow," he said. "So there is one heck of a push amongst the U.S.-based unions to ensure that their members can never leave their union."

Unite Here Local 75 outlined several frustrations with its parent Unite Here when announcing the vote to switch unions. It said Unite Here put the local into trusteeship in January, removed elected officials and seized the local unit's assets.

Unifor is the product of a variety of unions that broke away from their American parent, said Ross. So their viewpoint is one that is very sympathetic to union members in situations like those that Unite Here Local 75 describes, she said, where they disagree with the parent chapter over the union's direction, including on upcoming collective bargaining.

Yussuff disagreed with Dias's assertions that the CLC has failed to act on member complaints, adding its received 46 complaints between May and December last year and all have been resolved. The group can't address complaints it doesn't receive, he added.

If Unifor has issues with the group's constitution, Yussuff said, the union should have worked within the system to build a consensus around how to improve the structure.

"Leaving and interfering in the relationship with other affiliates is not a way to demonstrate your solidarity."