Striking Boeing workers have rejected a new offer from the plane-making giant, which included a 35% pay rise over four years.
The International Association of Machinists and Aerospace Workers (IAM) union said 64% of its members voted against the proposed deal.
More than 30,000 of Boeing’s employees have joined the walkout, which started on 13 September, after an initial offer was rejected.
Hours earlier Boeing’s boss Kelly Ortberg warned that the company is at a “crossroads” as losses at the firm surged to roughly $6bn (£4.6bn).
“After 10 years of sacrifices, we still have ground to make up, and we’re hopeful to do so by resuming negotiations promptly,” union representatives said in a statement.
“This is workplace democracy – and also clear evidence that there are consequences when a company mistreats its workers year after year,” it added.
Boeing has declined to comment on its latest offer being rejected.
It is the second time that the striking workers have rejected a proposed deal in a formal vote. The previous offer was turned down last month by 95% of workers.
The latest crisis at Boeing erupted in January with a dramatic mid-air blowout of a piece of one of its passenger planes.
Its space business also suffered a reputational hit after its Starliner vessel was forced to return to Earth without carrying astronauts.
The strike has compounded the problems, leading to a dramatic slowdown in production.
Boeing’s commercial aircraft business reported operating losses of $4bn in the last three months, while its defense unit lost nearly $2.4bn.
The company announced plans earlier this month to cut roughly 10% of its workforce. Thousands of other staff are already on a rolling furlough due to the strike, which has also hit suppliers.
Boeing’s suppliers are also feeling the impact of the strike.
