KITTERY – Union members, politicians and Portsmouth Naval Shipyard workers are expected to turn out Saturday for a five-town, two-state “rolling rally” that will mark the last major public plea to keep the Kittery yard open before a new closure list comes out.

The rallies are organized by the Seacoast Shipyard Association, which formed in 1964 to fight a base-closure proposal from then-Defense Secretary Robert McNamara. Since then, the group has helped to prevent three possible closures.

Now, shipyard supporters are looking ahead to May 16, the deadline for Defense Secretary Donald Rumsfeld to submit a list of recommended base closures to the Base Realignment and Closure Commission.

If the Portsmouth shipyard is on the list, its roughly 4,800 employees will live under the threat of closure until at least early September, when the nine-member commission sends its base-closure recommendations to President Bush.