Rumsfeld and Gen. Richard Myers, chairman of the Joint Chiefs of Staff, are to testify Monday before a congressionally chartered commission that will review the base closing proposal before sending it to President Bush this fall.
The plan recommends closing or reducing forces at 62 major bases and reconfiguring 775 others to save billions of dollars a year.
Here is a look at how the specter of the closings is affecting nine communities across the nation:
In Washington, D.C., the venerable Walter Reed army hospital is slated to be closed, reports CBS News Correspondent Joie Chen. The first stop on home turf for the most battered survivors of war, it has treated thousands of soldiers wounded in Iraq. Private Jessica Lynch came here to recuperate. So did "B-D"-- the Doonesbury character who lost his leg to a grenade in Iraq.
Walter Reed has been the nation's premier military hospital for 96 years.
Heroes like General John Pershing and future president General Dwight Eisenhower were patients.
Closing Walter Reed would be a huge symbolic loss for Washington, and would slash nearly 6,000 local jobs.
The Pentagon plans to consolidate the hospital with another in nearby Maryland to create the new Walter Reed National Military Medical Center. Many former staff members support the move, because the cutting-edge new facility would replace the current cramped corner.
Local leaders have vowed to fight the move, but the district is handicapped because it does not have statehood or a senator to lead the fight in Congress.
In Groton, Conn., real estate agent Nancy Warburton wasn't thinking about billions of dollars in lost military spending following the Pentagon's announcement that it plans to close the Naval Submarine Base. She had just one figure in mind:
That's the number of clients who said they were putting off buying homes.
"They said they wanted to wait and see what would happen," Warburton said. "Do you think I want to call them this afternoon and see if they want to go look at houses?"
If those two people don't buy a home, that's two fewer trips to the furniture store, two new lawn mowers or televisions that don't get purchased and two fewer commissions for Warburton, who in turn has less money to spend.
Economists call it the multiplier effect.
Retired 20-year Navy veteran Ed Putnam and others said they worried about how the town would respond to the loss. Putnam, who works on the base, has seen this submarine town weather a slow, steady reduction in the size of the fleet.
"We survived," he said. "I don't know how we're going to survive now."
But in a town that has overcome previous efforts to close the base, people know that first decisions in Washington are not always final.