PORTLAND – Union membership stands to take another major hit if the government’s proposal to close the Portsmouth Naval Shipyard in Kittery survives challenges by Maine elected officials.

Unions could lose more than 4,000 members if the shipyard closes. Three major labor organizations covering 2,300 tradespeople, 1,400 engineers and technicians, and 500 secretaries, police officers and other employees would be affected. Average pay at Portsmouth is about $65,000 annually.

The loss of union workers would continue a trend of organized labor losing its base in Maine. The state had 78,100 union members in 2000. That number fell to 63,700 last year, even as the state’s overall workforce grew, according to federal labor statistics.

Many of the job losses have been in paper-making, shipbuilding and other manufacturing jobs.

“We have suffered some major hits with mill closings, but this would be bigger than those,” said Edward Gorham, president of the Maine AFL-CIO.

The Pentagon has also proposed a major curtailment at Brunswick Naval Air Station and closing the Defense Finance Accounting Service office in Limestone.

The commission must make a final recommendation of which bases to close by Sept. 8. President Bush can either accept or reject the list in its entirety. It then becomes final unless Congress rejects it, also in its entirety.

Members of the Base Realignment and Closure Commission plan to visit the Kittery submarine repair facility on Wednesday and the Brunswick base Thursday. Gov. John Baldacci said efforts were under way to also arrange a BRAC visit to the Limestone facility.

Union leaders are reluctant to talk about a future without the Kittery shipyard, focusing instead on trying to get it removed from the list of military bases to be closed nationally.

“I’m not thinking about what would happen to me and the union. I am not going there right now,” said Paul O’Connor, president of the shipyard’s Metal Trades Council, which has 2,300 members.