It's either fitting or ironic -- or both -- that this Labor Day week is the likely backdrop for a local union vote that's attracted national attention.

Several hundred production employees at the Boeing Co. 787 fuselage plant at Charleston International Airport are set to decide Thursday whether to nullify the election that made them part of the International Association of Machinists and Aerospace Workers.

The casting of ballots, if it proceeds as scheduled, will be monitored by the National Labor Relations Board. Also watching closely will be Seattle business boosters, who are worried sick that more Boeing jobs will end up in South Carolina if the IAM doesn't get out the vote.

Should the workers void the 2007 election and disband their union, Washington officials fear that would give North Charleston a big leg up in the chase for a new assembly line for the long-delayed 787.

Puget Sound is, and hopes to remain, the backbone for all of the heavy lifting when it comes to assembling Boeing commercial airplanes, including what some critics have called the "7-Late-7."

But the company's relations with the strike-prone IAM have been strained, to put it delicately. Last year, a union walkout idled the company's Everett, Wash.-based aircraft division for eight weeks.

That largely anti-union South Carolina could snatch more of Boeing's business has left officials sleepless in Seattle, which is fiercely protective of its place in aviation manufacturing.

The reaction, in some cases, hasn't been kind to the Palmetto State.

Speaking at a business luncheon last week, North Charleston Mayor Keith Summey took offense at some of the snide verbal volleys that have been lobbed from Northwest about the quality of South Carolina's work force.

Summey challenged those critics to find a single defective ship that local hands built at the Navy base in his city.

"It won't happen," he said.

Summey also declined participate in the name calling.

"I don't think it's going to make my wife look any better by saying how ugly your wife is," he quipped.

Amid this war of words, Boeing has been posturing and reposturing as the union vote approaches.

Just a couple of weeks ago, it fired what appeared to be a shot across the IAM's bow by saying it will seek permits to build the second 787 line in North Charleston. But the company also stressed that the step was merely a precaution, just in case it picks the Lowcountry for the sought-after jobs and investment.

Boeing noted that other cities are being considered for the 787 expansion, but it has not identified any aside from ... Seattle. A decision is expected by the end of the year.

Meanwhile, the company also has had a change of heart about its union dealings since disclosing the $1 billion purchase of Vought Aircraft's local plant two months ago. Boeing said at that time it would negotiate a new contract if the workers vote to stick with the IAM. The company said further that it had no position on the outcome of the election.

More recently, Boeing has publicly stated that it would rather handle labor issues internally, not through a union.

It's also organized meetings to provide information to IAM members.

"We've told employees that Boeing's preference is to deal directly with (them) without intermediaries, but we've also told them we will respect the decision of the majority," Boeing spokeswoman Candy Eslinger told TheStreet.com for a report published last week.

Whether the vote will even take place this Thursday is about as uncertain as when the 787 will make its first flight.

A union official filed an unfair labor practice complaint against Boeing a week ago, saying the company had "unlawfully" changed the terms of employment at the local plant by imposing new access restrictions on IAM representatives. This latest wrinkle could delay the election.

As the nation's least-unionized state, South Carolina has never been big on recognizing Labor Day for its intended purpose. But this year, at least, there's a pretty good reason to pay a little more attention to it.