Early voting on the contract, reached on 10 October after a six-hour strike, seems mixed. Chrysler executives said on Friday 19 October that they expect the vote to be close, though they believed the pact would be approved. Voting ends next week. The outcome could determine how things go at Ford Motor, the last of the three big Detroit companies to negotiate with the UAW.

Union leaders approved the Chrysler agreement on Monday, despite opposition from local leaders including Bill Parker, who led the union''s bargaining committee. Parker''s biggest objections are a two-tier wage structure and new job classifications that would result in lower wages for workers at three plants.

The dissidents also say that Chrysler''s future investments that do not seem as secure as those at General Motors (GM), where workers approved a new contract last week. But at GM, workers aren''t protected from temporary layoffs. This week, GM said it would eliminate shifts at plants in Pontiac, Michigan, and Detroit, because of slower sales.

So it looks like for the first time in decades, there''s a very real possibility of rejection of a union contract. But UAW leaders have already begun to lobby local leaders to push for approval of the agreement. Some contract details are still to be finalised, and the company could come up with assurances or provisions at particular plants that could help swing the vote in favour of the contract.

But if the contract still seems headed for defeat, the union could suspend the voting and go on to Ford in hopes of reaching an agreement there. At Chrysler''s St Louis North plant, which produces pickups, workers overwhelmingly rejected the contract on Thursday. But a smaller plant in Kenosha, Wisconsin, approved it.

The St Louis South factory in Fenton, Missouri, which builds minivans and might face severe cutbacks if not a shutdown, was scheduled to vote late on Friday. Other plants voting over the weekend include Trenton, Michigan; Twinsburg, Ohio; and two plants in Detroit.

It is rare for UAW members to reject a tentative agreement, and union leaders are usually careful not to send out a contract that might be defeated. For approval, the contract must get a simple majority of workers'' votes.

The UAW does not release vote totals, only percentages. At GM, for example, 66 per cent of assembly workers and 64 per cent of skilled trades workers voted in favour of the contract.

But Chrysler has a history of worker dissent. In 1982 - three years after workers granted concessions to help the company avoid bankruptcy - union members defeated a contract that would have given them profit-sharing payments instead of immediate wage cuts.

In 2005, UAW leaders did not reach a separate deal on health care cuts at Chrysler as it did at GM and Ford, because it seemed likely that Chrysler workers would not approve the cuts. Earlier, Ford workers had approved the cuts by only a 51 per cent margin, despite the company making deep losses.