While Boeing Co. considers locating a second assembly line for the 787 Dreamliner locally, some workers at its North Charleston plant will decide today whether to remain part of the union that stalled production at the company's existing Seattle factory.

The vote could decertify the election that made them members of the International Association of Machinists, which staged an eight-week strike last year that compounded delays in producing passenger jets at the Puget Sound assembly line.

Seattle-based aviation analyst Scott Hamilton said cutting IAM out of local operations would cast a favorable light on the Lowcountry in Boeing's eyes but would guarantee nothing if the company expands its 787 production.

"I think it's important to emphasize that decertification does not, in my view, mean that line two is an assumption for Charleston," Hamilton said. "A lot of other factors are involved, not the least of which is a risk factor of establishing a brand-new line down there with new hires that have to be trained in the complicated process of assembling a complete and operational airplane."

Hamilton expects the majority of union members to vote in favor of disbanding today, given the slim margin under which the union was formed and then a contentious contract ratification that virtually excluded rank-and-file members.

He said IAM leaders might try to reorganize, or another union could move in if the election dissolves the existing structure.

"You're not going to have a plant like that with a company like Boeing and not have some union try to organize," Hamilton said.

IAM organized production workers at the factory off International Boulevard while the plant belonged to Vought Aircraft Industries, which made aft fuselage sections for the long-delayed 787. Boeing purchased the operation in a $1 billion deal in late July.

Boeing spokeswoman Candy Eslinger discounted theories that the outcome of today's vote will shape the company's decision on where to expand.

"That's all been public speculation," she said. "There is no connection between the vote and the location on a second line."

Boeing has said it is studying several sites for a second 787 assembly plant, including North Charleston and its existing manufacturing hub outside Seattle. A decision is expected by the end of the year.

Eslinger said just fewer than 300 workers in North Charleston are covered by the union contract and are eligible to vote today. Boeing recognized the IAM when it bought out Vought, but by law Boeing does not have to assume Vought's labor contract.

The aerospace giant planned to renegotiate with the union and the employees but, in the meantime, one of them filed a petition to decertify the IAM election, which was held in October 2007.

Dennis Murray, a quality inspector from Summerville, said the IAM made promises at that time but the vote on the labor contract a year later took place in an emergency meeting attended by only about 12 union members. He said that deal with Vought reflected a cut in benefits.

"We were getting the short end of the stick all the way around," Murray said. "A lot of people were unhappy with it, and a group of us decided to do something about it."

Dallas-based IAM spokesman Bob Wood said workers need the union to safeguard their jobs. He plans to attend the vote.

"The biggest thing is that the workers have no protections," he said. "There's nothing they can do. The company can get rid of people for no reason and not bring them back."

Wood also said the talk about building the second 787 assembly line in North Charleston could amount to little more than anti-union posturing.

"You can make big promises and everything, but they aren't putting anything on paper," Wood said. "I think anybody could see through it. It's a pie-in-the-sky thing in hope to get votes."

Representatives from the National Labor Relations Board will conduct a secret-ballot election between 1:30 and 5 p.m., according to the board's assistant regional director, Howard Neidig, who works in Winston-Salem, N.C. Union members will answer whether they want to be represented by the IAM.

Neidig said the union needs a majority voting "yes" to remain in place. A tied vote translates to decertification.

In order for the board to take up Murray's cause, he had to show he had support from at least 30 percent of the union's members, Neidig said.

Murray said he gathered about twice as many names as he needed.

The public cannot observe the vote, but the results are expected to be disclosed tonight.