Workers today picket in front of the entrance to the GM Pittsburgh Metal Center in West Mifflin, Pa. Thousands of United Auto Workers walked off the job at GM plants around the country today, in the first nationwide strike during auto contract negotiations since 1976. AP Photo/Post-Gazette, Darrell Sapp

UAW President Ron Gettelfinger said that job security was the top unresolved issue, adding that the talks did not stumble over a groundbreaking provision establishing a UAW-managed trust that will administer GM's retiree healthcare obligations. Gettelfinger complained about "one-sided negotiations."

"It was going to be General Motors' way at the expense of the workers," Gettelfinger said at a news conference. "The company walked right up to the deadline like they really didn't care."

Gettelfinger added that the union and GM's management would return to the table Monday.

Workers walked off the job and began picketing Monday outside GM plants after the late-morning UAW strike deadline passed. The UAW has 73,000 members who work for GM at 82 U.S. facilities, including assembly and parts plants and warehouses.

General Motors Corp. had been pushing hard in the negotiations for the healthcare trust — known as a Voluntary Employees Beneficiary Association, or VEBA — so it could move $51 billion in unfunded retiree health costs off its books. GM has nearly 339,000 retirees and surviving spouses.

"This strike is not about the VEBA in any way shape or form," Gettelfinger said at an afternoon news conference in Detroit.

"The No. 1 issue here is job security," Gettelfinger later said, adding that the union also was fighting to preserve workers' benefits.

GM spokesman Dan Flores said the automaker was disappointed in the UAW's decision to call a national strike.

"The bargaining involves complex, difficult issues that affect the job security of our U.S. work force and the long-term viability of the company," he said. "We remain fully committed to working with the UAW to develop solutions together to address the competitive challenges facing GM."

It remained to be seen what effect the strike would have on the automaker and consumers. The company has sufficient stocks of just about every product to withstand a short strike, according to Tom Libby, senior director of industry analysis for J.D. Power and Associates.

Worker Anita Ahrens burst into tears as hundreds of United Auto Workers streamed out of a GM plant in Janesville, Wis.

"Oh my God, here they come," said Ahrens, 39. "This is unreal."

Ahrens has seven years at the plant, where she works nights installing speakers in sport utility vehicles. She waited outside the building Monday for her husband, Ron Ahrens, who has worked there for 21 years.

The couple has three children, including a college freshman, and Ahrens worried about how they would pay their bills.

"This is horrible, but we're die-hard union, so we have to," Ahrens said. "We got a mortgage, two car payments and tons of freaking bills."

Gettelfinger said he believed the UAW's leadership owed "our membership an answer as to why they're out there."

"This is as serious as anything that any of us do," he said. "There's not one person on this stage ... that wanted to see these negotiations end in a strike. Who wins in a strike? But again, you can be pushed off a cliff, and that's what we feel like happened here."