Boeing's CEO said Wednesday that the company will begin furloughing "a large number" of employees to conserve cash during the strike by union machinists that began last week.

Chief Executive Kelly Ortberg said the layoffs would be temporary and affect executives, managers and other employees.

About 33,000 Boeing factory workers in the Pacific Northwest began a strike Friday after rejecting a proposal to raise pay by 25% over four years. They want raises of at least 40% and other improvements in the deal that they voted down.

The furloughs are expected to affect tens of thousands of Boeing employees. Ortberg said employees will be furloughed for one week every four weeks, and he and other senior executives will take pay cuts during the duration of the strike.

The strike is halting production of several Boeing models, including its best-selling plane, the 737 Max. The company gets more than half of the purchase price when new planes are delivered to buyers, so the strike will quickly hurt Boeing's cash flow.

Ortberg said in a memo to employees that the company is talking to the International Association of Machinists and Aerospace Workers about a new contract agreement that could be ratified.

"However, with production paused across many key programs in the Pacific Northwest, our business faces substantial challenges and it is important that we take difficult steps to preserve cash and ensure that Boeing is able to successfully recover," he said.

Boeing's chief financial officer warned employees earlier this week that temporary layoffs were possible. The company, which is based in Arlington, Virginia, but has most of its commercial-airplanes business located in the Pacific Northwest, is also cutting spending on suppliers, freezing hiring and eliminating most travel.