WASHINGTON — A plan to have Navy destroyers built at a single shipyard needs more study, a top Pentagon official said Wednesday, temporarily ending fears that Bath Iron Works could lose its share of work on new stealth destroyers now nearing production. Dugan Shipway, president of BIW, called the determination "an encouraging sign."

Maine Sen. Susan Collins agreed but said she would pursue legislation to prevent the Defense Department from changing its strategy for building the so-called DD(X) destroyers.

"It's a positive step forward that supports our efforts to block the one-shipyard acquisition strategy for the DD(X)," said Collins, a Republican and a member of the Armed Services Committee. "It is not the final word on the issue, but it certainly is good news that a high-level Pentagon official who has responsibility for acquisition policy has reservations. That is very encouraging."

Shipway, who met Wednesday with Collins, said the finding - contained in a memo written by Michael Wynne, the Pentagon's undersecretary for acquisition - means there will be no decision about a single shipyard until the Navy studies the ramifications further.

"This is a signal that (the Navy) is not quite ripe for any decision yet," he said.

Sen. Olympia Snowe, R-Maine, called the announcement "proof that they recognize the need to step back to re-evaluate this ill-advised one-shipyard policy. Maintaining multiple shipyards is absolutely vital because we cannot foresee how many destroyers we will need in the future."

Wynne's memo came one day after a congressional hearing at which Navy Secretary Gordon England defended his proposal to consolidate destroyer construction at a single shipyard. Wynne is higher in the chain of command than England, though England has been nominated to become deputy defense secretary, the second-highest official at the Pentagon.

BIW and the Northrop Grumman Ingalls shipyard in Mississippi have shared destroyer construction for years, but BIW seemed most vulnerable to a switch to a single yard. Ingalls had already won the competition to design the DD(X) and would have been favored to win the construction contract, leaving Bath scrambling to find work for its 6,200 employees.

England maintains the Navy could save $300 million per ship by reducing the overhead of supporting both shipyards. But critics contend that having a single builder for surface warships would leave the country vulnerable to everything from price hikes to hurricanes.

The single-yard debate took on even greater significance after the Navy cut back its plans for destroyer construction, with only five planned over the next six years rather than the 12 sought a year ago.

In his memo, Wynne authorized the Navy to seek further industry comment on the strategy of having a single shipbuilder.

"However, at this time, I consider it premature to change the shipbuilder portion of the acquisition strategy which I approved on February 24, 2004," Wynne wrote.

Collins, meanwhile, is trying to prevent a winner-take-all strategy through legislation attached to the $81 billion in emergency funding for Iraq and Afghanistan that Congress is now debating. Her provision is included in the Senate version of the bill but not the House version. The White House has not taken a position.

"It's encouraging to have the person in charge of acquisition strategy for the Department of Defense listen to the concerns that we've been raising," Collins said. "Apparently he shares at least some of our reservations, or otherwise he would have just given a green light to the project. What he's done is turned on a yellow light. This is certainly good news, but it's not the final decision."

Michael Keenan, president of the machinists union in Bath, said the memo was welcome news on a day when 32 workers were laid off.

"It's something to give hope to the thousands of shipbuilders that have vested many years at Bath Iron Works," he said. "It'll also keep our craftsmen within the shipyard instead of looking for opportunities outside the shipyard."

Shipway also repeated his commitment to keep BIW operating. He agreed that the yard could build Coast Guard ships at some point in the future, but said he is not interested in taking away work from another company lined up to build those ships at this time.

"We will look for opportunities every place they are," he said. "BIW is going to be here for decades into the future. We build destroyers. We hope to be able to build more destroyers in the future, more DD(X), and maybe Coast Guard cutters."