Boeing’s latest offer of a 30% wage increase over four years was rejected by workers in Seattle on September 24, who have been on strike since September 13.

The International Association of Machinists and Aerospace Workers (IAM), which represents 33,000 striking Boeing employees, has been demanding a 40% wage hike over three years. This is the first full contract negotiation with Boeing in 16 years, according to the Associated Press.

In a statement, IAM declared that 94% of its members, from District 751 and District W24, voted to reject Boeing’s offer. “We want to return to the negotiating table as soon as possible to secure a contract that our members accept and deserve. This is our future and our fight,” the union said.

According to Bloomberg, the union described the latest offer as “inadequate” and “disrespectful” after a member survey showed strong disinterest in the proposal.

Boeing’s offer, labelled as its “best and final,” included an increase in pay raises from 25% to 30% over four years, featuring an upfront 12% hike and three annual 6% increases. It also doubled ratification bonuses to $6,000 and retained annual productivity-based bonuses.

However, Boeing’s earlier proposal to replace productivity bonuses with retirement contributions remained a point of contention, contributing to the union’s decision to reject the deal.

Also Read: Boeing says it’s considering temporary layoffs to save cash during the strike by machinists

Boeing said average annual pay for machinists would rise from $75,608 now to $111,155 at the end of the four-year contract. The new offer would not restore a traditional pension plan that Boeing eliminated about a decade ago. Striking workers cited pay and pensions as reasons why they voted 94.6% against the company’s previous offer. Boeing also renewed a promise to build its next new airline plane in the Seattle area — if that project starts in the next four years.

Later, Boeing also gave the union representing striking factory workers more time to consider a revised contract offer with bigger pay increases and more bonus money.

The striking workers said the latest offer wasn’t good enough and also complained about the way Boeing bypassed the union in publicising the offer, with some workers saying it was an unfair attempt to make them look greedy.

The strike has halted production of Boeing’s best-selling 737 MAX jets, along with its 777 and 767 widebody aircraft, delaying deliveries to airlines.

Boeing has imposed a hiring freeze and started furloughs for thousands of US employees to reduce costs. A prolonged strike could cost several billion dollars, fraying the planemaker’s already strained finances and threatening a downgrade of its credit rating, reports suggest.

(With text inputs from AP)