Boeing workers in the Seattle area on Wednesday overwhelmingly rejected the latest four-year labor contract agreement proposed by industry management and voted to continue their strike that has paralyzed two critical factories since in mid-September, their union body announced.

64% of local IAM members opposed the proposal, the union said via X. Boeing management’s most recent offer included wage increases of 35% over four years, but without restoring the pension system that was abolished in 2008, a demand of many of its employees.

The decision to put further pressure on the US aerospace giant’s management reflects years of resentment among many workers, who feel they were cheated a decade ago, and deepens problems for Boeing, which was already in crisis.

More than 30,000 workers have gone on strike at factories on the US West Coast since September 13, halting production of its most sought-after aircraft, the 737 MAX, as well as its larger 767 and 777 models.