SEATTLE—Factory workers represented by the International Association of Machinists have voted to reject Boeing’s latest contract offer and continue their strike, which has now lasted more than five weeks.

The vote was 64 percent in opposition to the deal, which offered a 35 percent rise in wages over four years.

The rejection of Boeing’s offer, which comes after 95 percent of workers voted against the company’s initial contract offer last month, reflects years of resentment from workers who felt cheated by the company in talks a decade ago. The union has been seeking a 40 percent pay rise and the return of the defined-benefit pension.

With Boeing and IAM at a stalemate earlier this month, acting U.S. Secretary of Labor Julie Su had helped get the latest offer presented for a vote after attending in-person talks with both parties in Seattle last week.

Fuselage supplier Spirit AeroSystems warned that if the strike continued beyond the end of November, there would be layoffs and more drastic furloughs. The company, which is in the process of being taken over by Boeing, has already announced a 21-day furlough for 700 workers.

Boeing has announced plans to cut 17,000 jobs and is closing in on a plan to raise up to $15 billion from investors to help preserve its investment grade credit rating, while some airlines have had to trim schedules due to aircraft delivery delays.