Ratification of the tentative labor contract between the United Auto Workers union and Chrysler LLC was thrown into jeopardy on Monday after workers at four of the eight assembly plants that must vote on the deal rejected it.

In total, six UAW-represented facilities representing about 11,150 workers have voted against the contract while nine others, representing 8,294 workers, have approved the proposed four-year contract, according to a tally provide to Reuters by a person opposed to the deal.

The deep-seated opposition to the Chrysler deal marks a setback for leadership of the UAW, which reached a tentative agreement with Chrysler on October 10 after a six-hour strike.

UAW President Ron Gettelfinger, who is waiting to negotiate a contract with Ford Motor Co, may have to go back to the bargaining table with Chrysler if the deal is rejected. Voting is expected to conclude this week.

Union dissidents, including some UAW local leaders, argue that the contract should be rejected because it would allow Chrysler to hire workers at half of current wages without guaranteeing new investment in U.S. factories.

UAW dissidents also object to a plan to create a trust fund to pay for health care for Chrysler retirees, saying it would be underfunded compared with Chrysler's estimated $19 billion obligation for those costs.

A majority of Chrysler's almost 49,000 UAW-represented factory workers must ratify the four-year contract for it to take effect.

A UAW spokesman could not immediately be reached for comment.

A four-year contract with General Motors Corp, which was unanimously backed by union leadership, was approved by 66 percent of GM factory workers.

UAW locals who rejected the Chrysler deal include those at Chrysler's Jeep assembly plant in Detroit, a component plant in Detroit, a minivan plant in Fenton, Missouri, a stamping plant in Twinsburg, Ohio, and an assembly plant in Newark, Delaware.

The St. Louis North plant, which makes the Dodge Ram truck, employs 2,330 workers and is Chrysler's third-largest U.S. facility, also rejected the deal.

Nearly 8,000 more workers employed at two Chrysler assembly plants in Sterling Heights, Michigan and Belvidere, Illinois have yet to vote, according to union locals.

Private equity fund Cerberus Capital Management took Chrysler private in August. Former owner Daimler AG maintains a roughly 20 percent stake in Chrysler.

Chrysler management has indicated that it will move forward with plans to cut up to five models from its lineup under an accelerated turnaround plan.