CAW president Ken Lewenza says his union and GM have until May 15 to reach a new deal. (Nathan Denette/Canadian Press)

The president of the Canadian Auto Workers said the union and General Motors Canada are being ordered back to the negotiating table by the Canadian and Ontario governments.

Ken Lewenza said the two governments have given the union and the company until May 15 to reach a new deal on concessions to help GM save money.

Lewenza said the governments want the union to make concessions similar to those they gave Chrysler. Without a new deal, he said, GM Canada won't be eligible for aid from the federal and provincial governments.

"If we don't get a deal, the governments will provide no financial support and GM Canada will be liquidated," Lewenza said at a news conference in Toronto.

The union said the governments' main issue focuses on GM Canada's so-called legacy costs such as pension obligations.

"Our responsibility as a union is to do whatever we can to preserve the jobs that we have left in General Motors and Canada because the only way you can protect the pensions long term is to continue to operate," said Lewenza.

"But it is absolutely impossible that we can correct the legacy costs at the bargaining table," he warned.

The CAW and GM Canada initially worked out a new labour deal in March, but Industry Minister Tony Clement hinted then that it might not be acceptable.

"We are telling them that they have to be viable and competitive and otherwise, as I understand it, they won't get a viability agreement in the United States and therefore government loans won't flow," Ontario Finance Minister Dwight Duncan said Thursday.

The March CAW-GM deal cut labour costs by about $7 an hour per worker, but the deal between Chrysler and union reduced the hourly costs by about $19 an hour.

With files from The Canadian Press