Canadian Auto Workers President Buzz Hargrove talks on a cellphone before entering a meeting with General Motors executives in Detroit, Mich., Friday. ((Dave Chidley/Canadian Press))

Autoworkers blockading General Motors' corporate offices to protest the decision to shut down its Oshawa, Ont., truck plant vowed to introduce "phase two" of actions against the automaker on Saturday.

"What I can guarantee, and I said this to General Motors about an hour ago on the highway, they want their building back and they're not getting their building back," Chris Buckley, president of Canadian Auto Workers local 222 in Oshawa, told a crowd of union supporters Friday.

Buckley requested all union members be at the site of the blockade Saturday morning, where they will announce how they will step up their action.

The comments came just hours after CAW president Buzz Hargrove came out empty-handed Friday after asking GM executives to reverse a decision to close the truck plant.

GM officials and Hargrove met in Detroit to discuss the announced closure.

"He is leaving with nothing," the CBC's Havard Gould said.

Hargrove met GM CEO Rick Wagoner and other company executives to discuss the decision, announced Tuesday. The company said the Oshawa plant is one of four North American plants closing because of falling truck sales.

GM 'pulled the rug out from under us': Hargrove

"I'm very, very disappointed," Hargrove told CBC News. "I've worked with these people for a lot of years and they pulled the rug out from under us here."  

As many as 2,600 jobs are at stake, and CAW members are continuing to blockade the Oshawa site to protest the planned closing, set for 2009. 

Hargrove says GM is disregarding the terms of a new collective agreement reached just last month, but the automaker says the soaring price of gas has hit pickup truck sales hard, with no relief in sight.

'Good exchange' at Detroit meeting:  GM

A spokesman for GM's Canadian operations, Stew Low, said the company understands the union's disappointment, but maintained there was a "good exchange" between the two sides at the Detroit meeting.

Low said the company did bargain in good faith for the latest collective agreement with the CAW, but demand for trucks and SUVs had plunged "rapidly and dramatically."

Angry union members reacted to the surprise closing announced Tuesday by setting up the blockade at GM headquarters.

Hargrove said he's determined to keep the truck plant open past 2009.

"We'll explore every avenue that's available to us," Hargrove said after the meeting with GM. "We think we have some legal grounds and we'll review all of our options with the local [union] leadership."

The CAW leader said those options included going to court and arbitration, but he wouldn't say whether any sort of strike action might be possible.

"I'm not going to speculate on that," he said.

General Motors executives have said their decision to close the Oshawa plant is within the terms of the three-week-old collective agreement.

Analysts have said there is a loophole in the agreement that allows GM take action if the market changes.

Truck sales off 39%: GM

Wagoner told a news conference in Wilmington, Del., on Tuesday that higher gasoline prices are changing consumer behaviour and rapidly affecting the auto industry sales mix.

"We at GM don't think this is a spike or a temporary shift. We believe that it is, by and large, permanent," he said.

As part of the consumer shift away from large trucks and SUVs, GM plans a 2010 launch of a new Chevrolet compact car, which will be built in Ohio. Wagoner also said the company has approved the launch of the Chevy Volt extended-range electric vehicle, which is tentatively slated to be built in Detroit.

Wagoner said GM is reviewing the future of the Hummer brand.

The company also said Tuesday that its U.S. sales of trucks in May were down 39 per cent compared to the same month last year. GM's overall sales of all vehicles were down 30 per cent year over year.

Closure 'a betrayal':  union

In May, the CAW reached an agreement with GM to postpone a 900-worker layoff at the Oshawa truck plant until September 2009.

Chris Buckley, chairman of the CAW's master bargaining committee with GM, said he felt betrayed by the company's latest move.

"We just ratified a new three-year collective agreement on May 16," Buckley said. "We gave General Motors some cost savings to remain competitive here in Canada. General Motors felt comfortable enough to agree with the tentative agreement. They committed to products in this plant … and as of today they've pulled that product out from underneath us. It's nothing short of betrayal."

Buckley is one of the leaders of the blockade of GM's Oshawa headquarters, and said the action will continue until the company reverses its decision to close the truck plant.

With files from the Canadian Press