The lead negotiator for the union's national headquarters, Rich Michalski, told The Seattle Times in a phone interview that a vote is set for Jan. 3, the newspaper reported Saturday.
The contract would secure work on Boeing new 777X airplane at a time when 22 states are vying for those jobs. The company says it expects to pick a location early next year.
The local union, District 751, said on its website Saturday that there's no stopping the vote and urged members to reject the contract.
"Despite objections from District 751 leadership, the International has insisted on a vote on January 3rd to ensure you spend your holidays studying and debating a concessionary proposal that is largely unchanged from the one you rejected by a 2-to-1 margin on Nov. 13," the statement said.
"We're adamantly recommending that our members reject the offer," local union spokesman Bryan Corliss said Saturday. "The timing will make it hard to get members information to make a decision."
National union spokesman Frank Larkin said Saturday the vote is being scheduled to respond to members who have been calling for one and in keeping with a long union tradition that members have the final say.
He added: "It's obviously a controversial proposal. There is a range of opinions. The vote will be by secret ballot and the members will have the last word."
Local leaders of the International Association of Machinists and Aerospace Workers have faced pressure in recent days for declining to put Boeing's last offer to a vote.
"The terms of Boeing's enhanced contract offer to the IAM on December 12 stand," Boeing spokesman Doug Alder said in a statement Saturday. "If ratified by the membership, Boeing would honor that contract."
Boeing has gotten proposals from 22 states covering 54 locations that all want to build the plane. Boeing says it is narrowing the list down and is telling each location its status in the process. Boeing isn't releasing the list publicly.
State officials in North Carolina said Boeing told them Friday that sites in Charlotte, Greensboro and Kinston were out of the running.
The 777X is expected to bring thousands of well-paying jobs to wherever it is assembled.
Boeing began looking for a new location to build the successor to its popular 777 after union workers in Washington state rejected a deal that would have kept the work there.
The latest round of contract talks collapsed earlier this month when local Machinists officials said they could not recommend Boeing's latest proposal to members.