Boeing Co. has asked 15 U.S. locations to submit formal bids for the work of building its forthcoming 777X jet, according to a person close to the discussions.

Boeing spokesman Doug Alder has confirmed that a formal request for proposals was sent out to "more than a dozen" sites late last week.

Boeing also said it is not in any talks with the machinists union to get past the rejection of its contract offer that ­precipitated the opening up of the site search.

Washington state is one of the 15 sites under consideration, said the person close to the discussions. Long Beach, Calif., and Salt Lake City are also on the list. The other locations include both existing Boeing locations and new "green field" sites.

Other sites likely to be on Boeing's list are Huntsville, Ala.; San Antonio; and North Charleston, S.C. The states of Kansas and Missouri have also recently declared interest. All have existing aerospace expertise and Boeing facilities.

Aviation analyst Richard Aboulafia of the Teal Group expressed skepticism that Boeing would choose a completely new location with no experience in airplane ­manufacturing.

"That's just really a bad idea," said Aboulafia. "You are adding multiple layers of risk both in terms of workforce and infrastructure."

Boeing did that on the 787 Dreamliner program when it chose South Carolina to build big fuselage sections.

That caused such delays and quality problems in the jet program's early years that the chief executives of both Emirates and Qatar Airways, whose orders launched the 777X earlier this month, declared in interviews there that they have told Boeing not to repeat that experience.

Casting a wide net for bidders does, however, "do a good job of motivating" the more established contenders, said Aboulafia. In his view, the best site by far remains Washington.