The Pentagon thinks it has a winning argument for why Congress should approve a new round of military base closings.

The case goes like this: The Army and Air Force have vast surpluses of space for training and basing troops, and trimming the excess would save money better used to strengthen the military.

But Congress has its own logic: Closing bases can hurt local economies, which can cost votes in the next election. Besides, some lawmakers say, the Pentagon has cooked the books to justify its conclusions — or at least hasn't finished doing the math.

Whatever the chances of success, the Pentagon is renewing its base-closing request. It's submitted a report to lawmakers that calculates a 22 percent surplus in base capacity.