DEARBORN, MICH., SEPT. 11 -- Talks between the United Auto Workers and Ford Motor Co. stalled today over union demands for a no-layoff clause in a new labor contract.

Ford has been chosen as the strike target in negotiations to replace three-year contracts at Ford and General Motors Corp. And "unless something begins to happen and happen quickly," the company could face a work stoppage at 11:59 p.m. Sept. 14 when the current agreements expire.

"This is a very critical period that we're moving into," UAW President Owen Bieber said this afternoon. "We have not resolved the job security issue ... . the tough issues are still all out there, and we're not making progress at the moment."

At the moment, arguments over the UAW's job security proposal are so intense, and progress is so slow, "I'm not very optimistic that we can reach our deadline," Bieber said.

Stanley J. Surma, Ford's chief negotiator, agreed that the union and company have now entered "a very difficult period of negotiations." But he expressed optimism that with "continued effort by both parties," a settlement can come before the strike deadline.

GM officials said today that they have agreed to an indefinite extension of their current contract with the UAW, subject to three days' notice of cancellation by either side. Talks at GM, now conducted mostly in subcommittee meetings, will resume in ernest after an agreement is reached at Ford.

About 335,000 GM workers are affected by the negotiations. Sources familiar with the negotiations at Ford and GM said today's developments are real, and not the usual posturing that takes place on the eve of expiration of industrial labor agreements.

"Bieber is serious about his job security proposal. It's been his main thing at the bargaining table," the source said.

The UAW's Ford proposal has sent shudders through the executive suites of domestic auto makers. In brief, the proposal calls for:

Establishing "guaranteed employment numbers" at all UAW-organized Ford plants and facilities, which now have 104,000 UAW-represented workers.

Extending the guarantees "to any other employes having a direct attachment to the active work force," including those people on temporary layoffs -- a provision that could add 4,000 workers to Ford's payrolls.

Preventing Ford from eliminating positions or slots for jobs lost through attrition -- retirement, illness, death, etc.

Eliminating layoffs for the three-year run of a new contract.

Establishing a moratorium on "outsourcing" -- the practice of using non-UAW suppliers for automotive components. (Ford now outsources 50 percent of its component work, compared with 30 percent for GM.)

The UAW's strategy is to win a contract at the more prosperous Ford, and to bring an identical or similar agreement to GM. That is called "pattern bargaining."

But all of GM's top officials have gone on record as saying that they will not accept an agreement that contains the job security proposals the union has put before Ford.

"That would put handcuffs on us," one GM official said