SEATTLE (Reuters) -Boeing factory workers voted to reject a contract offer and continue a more than five-week strike on Wednesday, in a blow to investor and management hopes of a resolution to the acrimonious dispute.

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

Union leaders said they were ready to immediately resume negotiations with Boeing on the first new contract since 2014, when the company used the threat of moving production of the new version of the 777 out of the region to push through a deal that ended traditional pensions.

"After 10 years of sacrifices, we still have ground to make up, and we're hopeful to do so by resuming negotiations promptly," leaders of the International Association of Machinists and Aerospace Workers said in a statement after votes were tallied.

More than 30,000 machinists downed tools in Boeing's West Coast factories on Sept. 13, halting production of the best-selling 737 MAX and 767 and 777 wide-body programs.

Many comments on social media and from workers outside voting stations had cast doubt on a deal. 

"As of right now, I think we have the upper hand on Boeing," said Manuel Munoz, a 20-year-old mechanic, before the results were announced.

Reuters spoke to 20 striking factory workers in the Seattle area either before or after they cast ballots. Three said they would accept the deal, 14 said they would reject the proposal and three were undecided.

Many workers are still angry about the last deal signed a decade ago.

"We're going to get what we want this time. We have better legs to stand on this time than Boeing," said Donovan Evans, 30, who works in the 767 jet factory outside Seattle. Evans, who said he doesn't expect the pension to come back, voted to reject the deal and is holding out for a 40% raise.