The United Auto Workers union announced Wednesday that it reached a tentative agreement with General Motors that could end a monthlong strike by nearly 50,000 workers.

A union council still needs to sign off on the package brokered by top union negotiators before the longest auto strike in a generation is called off. If the council approves it, it would go to the full membership for a ratification vote.

The strike could end as early as Thursday, when the council is set to meet. But union leaders may decide to continue the work stoppage until members officially ratify the proposal, which could take days.

GM employees walked off the job on Sept. 16, shortly after their previous contract with the company expired. Since then they have forgone hundreds of millions of dollars in wages, while GM lost more than an estimated $1 billion in profits due to the work stoppage. The workers have maintained picket lines day and night at every unionized GM facility in the U.S.

By presenting an offer to the council for approval, the union’s negotiating team may feel they have moved the company as far as they can. Indeed, previous updates from the union and GM suggested they had made progress on key sticking points, including a pathway to permanent employment for temporary workers.

The two sides had been hung up for weeks on the pay scale for newer GM workers and a commitment to keep work inside U.S. plants, according to letters the UAW sent to members in October.

But the fact that the negotiating team has reached a possible deal does not mean the workers will approve it. In 2015, UAW members rejected a tentative four-year deal reached with Fiat Chrysler, which, like GM now, was the first of Detroit’s Big Three to bargain that year with the union. The no vote forced the union back to the bargaining table to secure a better agreement that pleased members.

The UAW may decide to keep the strike going until ratification is complete, just to avoid a messy situation in which the work stoppage ends but workers reject the proposal.

Many workers told HuffPost they still remembered the sacrifices the union made a decade ago when GM was facing bankruptcy, and they expected a larger share of the pie now that GM was doing so well. The company had pre-tax profits of nearly $11 billion last year.

As for GM, the company was intent on keeping labor costs down as U.S. auto sales slow and it makes investments in electric vehicles. The company infuriated workers late last year when it announced plans to idle four U.S. assembly and transmission plants, leading to layoffs or relocations for thousands of employees ― a move widely seen as an opening shot in this year’s labor negotiations.

Reaching a deal with GM would make it likely the union could also firm up agreements with Fiat Chrysler and Ford relatively soon. The UAW engages in “pattern” bargaining with the three automakers, a system in which the first contract tends to set the general terms of the other two that follow. The union represents roughly 150,000 hourly workers at all three companies.