BRUNSWICK — The effort to save the low-cost shopping commissary and exchange stores for residents with military ties took another step forward this week.

On Tuesday, U.S. Sens. Olympia Snowe and Susan Collins announced they have proposed legislation that will keep open the Navy Exchange Service Command store at Brunswick Naval Air Station and the Defense Commissary Agency at the Topsham annex beyond their scheduled closure in March 2011.

The state’s congressional delegation has jumped behind a local effort to save the shopping centers, which offer discount items to families of active and retired military members.

“The simple fact of the matter is that the commissary and exchange programs are an extraordinarily valuable portion of the compensation benefit for military service to the nation,” Snowe said in a press release.

“The Topsham commissary and Brunswick exchange are not only an important benefit for the active duty military personnel that will support continuing military missions in Maine’s Mid-Coast region and deploy overseas for wartime operations,” she said, “but the many other patriots and their families who have rightfully earned the benefit these stores provide for their service and sacrifice, including the families of those who have made the ultimate sacrifice in wartime, 100 percent disabled veterans, retired military members and their families, National Guardsmen and military reservists.”

Last September, Under Secretary of Defense Gail H. McGinn affirmed a U.S. Department of the Navy/Defense Commissary Agency decision to close the commissary and exchange. McGinn said the number of servicemen left behind after BNAS closes next year wouldn’t support the cost to operate the commissary and exchange.

According to their press release, Snowe and Collins are trying to save the commissary and exchange by inserting language into the defense authorization bill for 2011.