The largest union at plane maker Boeing says its members have rejected the company's contract offer and voted to strike.
But the union agreed to postpone a walk-out for 48 hours to allow more time for negotiations.
The International Association of Machinists leadership announced the deadline extension, which means Boeing employees will stay on the job until Friday, after saying that 87% of its members voted to start a strike at midnight on Wednesday.
If a deal for a new three-year contract is not struck by Friday, nearly 27,000 Boeing workers will start a strike that would cost the company about $100m in revenue a day as customers' planes sit idle on production lines.
A walkout would mark the fourth strike in 20 years for The International Association of Machinists and Aerospace Workers (IAM) - mostly based in Boeing's commercial plane plants in the Seattle area.
A strike would also put a dent in the US economy, swelling jobless claims and increasing inventories at major Boeing suppliers.
