Wichita ? Just days before a deal-breaking union vote that could derail the sale of The Boeing Co.’s commercial aircraft operations in Kansas and Oklahoma, the Canadian buyer told machinists Friday that letters telling them whether or not they have a job offer are in the mail.

Onex Corp. – through its newly formed subsidiary Mid-Western Aircraft Systems – told the Wichita plant’s nearly 6,000 machinists in a memo that they will receive letters at their homes today indicating whether they would be offered jobs with the new company.

Machinists who receive an employment offer will be told in the letter to report to work as usual on Monday, according to the memo. As many as 2,000 people could receive letters saying they won’t be hired. Those workers will be told not to report to work Monday but will continue to receive pay and benefits through Boeing until the sale closes, the memo said.

The letters are going out only to the Wichita plant’s machinists, whose union has completed contract negotiations. Machinists at Boeing’s Oklahoma facilities are represented by a different union. Onex must negotiate eight labor contracts with the seven unions representing workers at the three facilities affected by the sale.

Workers and their unions were caught by surprise by the timing of the job offers and the decision to bar workers not hired by the new company from their Boeing jobs on Monday.

Last month, Boeing sent 60-day layoff notices to 9,300 workers at its plants in Wichita, Tulsa and McAlester, Okla. Those layoffs had been scheduled to start last week and continue through May 27.

But last week workers received another memo telling them that the layoffs would occur between June 2 and June 15 after the sale was completed.

“I don’t know how having a clearer view of the future is applying pressure to the union vote,” said Boeing spokesman Craig Martin. “Our commitment is to tell employees everything we know as soon as we know, and this is just playing out that commitment in this particular regard.”

Martin said he did not know how many machinists would lose their jobs.

Onex officials could not immediately be reached for comment.

The offers come on the brink of Tuesday’s vote by Boeing’s largest union on a contract proposal from Onex asking workers to accept a 10 percent pay cut and agree to other concessions.

The International Association of Machinists and Aerospace Workers has said the company plans to offer jobs to between 4,000 and 4,500 of its nearly 6,000 at the Wichita plant.

A representative from the machinists union did not immediately return a phone call for comment.

But Bob Brewer, Midwest director for the Society of Professional Engineering Employees in Aerospace, called it “another botched attempt” at trying to move the sale of the Wichita plant forward.

SPEEA, which is still in negotiations with Onex, expects to have a final contract offer from the company next week, and will put it before the union’s membership the week after that, he said.

While the latest move by Onex does not directly affect the engineers and other professionals SPEEA represents, it is being closely watched by that union, which expects similar treatment as it winds up negotiations.

“We are outraged at the way the employees are being treated at the Wichita facility,” Brewer said. “This is the same old outdated, mean-spirited, misguided management tactics we have seen in the past.”

Onex agreed earlier this year to buy Boeing’s huge commercial aircraft plant in Wichita, plus other sites in Tulsa and McAlester, Okla., for $900 million cash and the assumption of $300 million debt. The sale is part of Boeing’s strategy to focus its commercial aircraft business on design and final assembly.

There would be changes at the plants even if the sale to Onex were to fall through. That could include downsizing the facility and work force or selling off parts of the whole plant, Martin said.

“We believe the sale to Onex is by far the best alternative to everyone concerned,” Martin said. “They are committed to working with the community. They look forward to investing substantial sums in the facility to make it more efficient and to winning new business which ultimately leads to more stable jobs and more jobs in Wichita.”