The United Auto Workers has set a deadline of 11 a.m. Wednesday to agree on a new contract with Chrysler LLC or workers could strike.

The deadline, confirmed Monday morning by Chrysler spokeswoman Michele Tinson, gives negotiators less than 48 hours until a strike could be called.

Bargainers returned to the table Monday morning after spending most of the weekend in negotiations.

Just because a deadline has been set doesn't mean a strike will happen, Tinson said. The union also could extend the contract hour-by-hour as negotiations continue, she said.

UAW spokesman Roger Kerson would not comment Monday on the possibility of a strike.

Progress was reported in weekend bargaining, but a person who had been briefed on the talks said that much work needed to be done on difficult issues. The person asked not to be identified because the talks are private.

The UAW represents about 49,000 hourly workers at Chrysler, making it the smallest of the three major domestic automakers. Chrysler has about 6,000 workers at three transmission plants and a casting factory in Kokomo, Ind.

A strike notice could be a tactic by the union to put pressure on the company as the talks intensify, said Harley Shaiken, a professor at the University of California at Berkeley who specializes in labor issues.

"The union wants the deadline to encourage a settlement sooner rather than later," Shaiken said. "I think the union may feel things are going well, but they want the discipline of a deadline," Shaiken said.

The UAW went on strike for nearly two days last month before coming to a tentative agreement with General Motors Corp. GM workers are expected to wrap up voting on the tentative agreement by Wednesday.

The union normally settles with one U.S. automaker and then uses that deal as a pattern for an agreement with the other two. But this year, both Chrysler and Ford Motor Co. have said they have different needs than GM and may need different contract terms.

A second strike in one set of negotiations would be rare, Shaiken said.

The last time the UAW struck two companies during the same set of negotiations was in 1976, according to Chrysler's fact book on the bargaining. The union walked out of Ford plants for 28 days in September and October, and for 12 hours at 16 key GM locations.

A short strike might not hurt Chrysler much. Five U.S. plants were scheduled to be shut down during the next two weeks due to lower market demand for their products. The shutdowns were expected to last one or two weeks.

The UAW's contracts with Chrysler, Ford and GM were originally set to expire Sept. 14. The UAW chose GM as the lead company and strike target and tentatively agreed to a contract on Sept. 26.

Chrysler has become a private company, which could be a factor in the talks. Private equity firm Cerberus Capital Management LP bought a majority share of Chrysler in August from DaimlerChrysler AG. As a private company, Chrysler no longer has shares and isn't required to file earnings reports.

Chrysler pays its workers an average of $75.86 per hour in wages, pension and health care costs, the highest among the Detroit automakers.

In addition to the 49,000 active workers, the company also has about 78,000 hourly retirees and surviving spouses.