Boeing’s Washington state factory workers will vote on Wednesday on whether to give their union a strike mandate as they seek a 40% raise in their first full negotiation with the planemaker in 16 years.

Many of the estimated 30,000 workers who build Boeing’s 737 MAX and other jets will rally in support of a mandate at Seattle’s T-Mobile Park, although they cannot strike before their contract expires on Sept. 12.

While the vote is considered procedural, the union is kicking off the 12 p.m. PDT event with fanfare, including an earlier convoy of workers on 800 motorcycles.

“It does empower the negotiating committee, it does send a strong message," union local president Jon Holden said about the vote during a June interview.