Seattle ? Boeing Co. and the machinists who assemble its commercial planes marked time through a long holiday weekend before Wednesday’s scheduled vote on the company’s “best and final” contract offer. Union leaders have called for rejection and a walkout.

Both sides said Monday there have been no new talks and none were scheduled.

Connie Kelliher, spokeswoman for International Association of Machinists and Aerospace Workers District Lodge 751, said large contingents of union members planned to march Wednesday morning to union halls in nearby Everett and Renton to vote together.

Results will be announced Wednesday evening. If the contract is rejected, picket lines would go up when the old contract expires, at 12:01 a.m. PDT Thursday.

Boeing Co. spokesman Tim Healy said the company has been available all weekend to answer any union requests for explanations or clarifications. He said the company is focused “on getting a positive outcome in the vote on Wednesday.”

The union represents 25,000 Boeing employees in the Seattle area, around 1,500 in Portland, Ore., and 750 in Wichita, Kan.

The proposal, Boeing’s third offer, was delivered to the union Thursday. It would increase pay by 11 percent on average over three years, the company said.

The offer also included a $2,500 bonus for workers if the agreement was ratified on Wednesday.

Boeing said it had withdrawn certain contentious proposals, such as plans to cut early retiree medical coverage and create a new defined-contribution retirement program for future employees.

The Chicago-based company hoped the proposal would help it avert a walkout. Contract negotiations came as Boeing tries to keep up with a backlog of plane orders and avoid more penalties caused by production delays of its next-generation passenger jet.

Machinists District President Tom Wroblewski said the company’s offer fell short in terms of job security, wages and medical coverage, among other areas.

Four union halls in the Seattle area were kept open all weekend so machinists could drop by and ask questions about the proposal, Kelliher said, adding the flow of inquiring employees was “pretty steady” on Saturday and Sunday but really slow on Monday.

Healy said Monday he thought the chances for a positive vote were good, adding, “It’s a great offer.”

On Wednesday, union members are scheduled to cast two ballots: one to accept or reject Boeing’s latest offer and another on whether to begin a strike. A simple majority is required to reject the contract, and a two-thirds majority is needed to call a strike, which would trigger a work stoppage.

The union’s main concerns include details on subcontracting, which union leaders say jeopardizes job security.

In 2005, about 18,400 machinists in the Pacific Northwest and Wichita struck for four weeks, forcing the company to halt commercial airplane production.

Analysts say a strike could cost Boeing about $100 million per day in deferred revenue. In 2005, Boeing was unable to deliver more than two dozen airplanes as scheduled because of that strike.

Besides the proposed wage hikes, the current offer included pension increases and a 3 percent cost-of-living adjustment. The added pay and benefits would total an average $34,000 over the life of the three-year contract, according to the company.