By David Shepardson

(Reuters) - Striking machinists at Boeing will vote Wednesday on a new contract proposal that includes a 35% pay hike over four years that could end a costly five-week-old strike, the company and union said Saturday.

Around 33,000 of Boeing's unionized West Coast workers, most in Washington state, have been on strike since Sept. 13. The work stoppage has halted production of the planemaker's best-selling 737 MAX and its 767 and 777 widebodies, putting added pressure on the company's already fragile finances.

The latest offer includes a $7,000 ratification bonus, reinstated incentive plan and enhanced contributions to workers' 401(k) retirement plans including a one-time $5,000 contribution plus up to 12% in employer contributions, International Association of Machinists and Aerospace Workers Local 751 said.

Boeing said Saturday it looks "forward to our employees voting on the negotiated proposal." Still there is no guarantee workers will approve the proposal after they overwhelmingly rejected an initial proposal. "The future of this contract is in your hands," the union told workers Saturday.

Boeing on Oct. 8 withdrew its enhanced offer that included a 30% wage increase over four years, after talks also attended by federal mediators broke down. The union has been seeking a 40% hike and restoration of a defined benefit pension, which was not offered in the new contract proposal.

In September, nearly 95% of the West Coast workers rejected Boeing's contract offer of a 25% pay rise over four years that had been endorsed by union officials, prompting the strike.

That earlier deal also had a $3,000 signing bonus which some Boeing workers told Reuters was too low, given that prior deals had bonuses of at least $5,000.

The union said on Saturday in a social media post that with the help of Acting U.S. Secretary of Labor Julie Su they had received a "negotiated proposal" and telling striking workers it "is worthy of your consideration."

On Monday, Su was in Seattle for her first in-person effort to help reach a new Boeing contract and returned on Thursday night to resume efforts after a trip to Detroit.

A spokesperson for Su said Friday the secretary was in Seattle having discussions with both parties and had met with Boeing CEO Kelly Ortberg and the union.

While some reaction on social media sites on Saturday morning were favorable to the new deal, it's not yet clear how the workers will vote.

A spokesperson for the White House said “President (Joe) Biden believes the collective bargaining process is the best way to achieve good outcomes for workers, and the ultimate decision on a contract will be for the union workers to decide.”