Defense Department officials warned a House panel Thursday afternoon that if Congress does not approve the Obama administration’s proposal for two new rounds of base closings, the Pentagon will use existing authority to close some facilities anyway.

“Communities would have to fend for themselves to a much larger degree,” Dorothy Robyn, deputy undersecretary of defense for installations and environment, told the House Armed Services Committee’s readiness subcommittee hearing on the request for additional Base Realignment and Closure (BRAC) rounds.

Robyn noted that the BRAC process requires the Defense Department to assist communities affected by closings.

Robyn said that the Defense Department has more than 300,000 buildings and 2.2 billion square feet of space — “more than Wal-Mart,” she noted.

“We are focused on getting rid of capacity we don’t need so we can use the resources elsewhere,” Robyn said.

The proposal came under bipartisan attack from members of the panel, who criticized the administration for making the proposal without providing any estimates of cost savings or other details.

“We need a lot more facts before we pass on another round of BRAC,” said Rep. J. Randy Forbes (R-Va.), chairman of the readiness subcommittee.

“I’m as concerned as others members in not knowing the cost,” said Rep. Silvestre Reyes (D-Tex.). “We’re moving in the dark with a request for two BRACs.”

Many in Congress are still licking wounds from the 2005 BRAC, the largest and costliest round ever, which resulted in 190 closures and realignments.

A Defense Department budget report submitted to Congress last month showed the total one-time costs for implementing the last round of BRAC was $35.1 billion, about 67 percent higher than the $21 billion the BRAC Commission estimated it would cost in September 2005. The higher figure is in keeping with estimates given in a 2009 Government Accountability Office report.

Recurring costs for the 2005 BRAC, including operation and maintenance, totaled more than $5 billion between 2006 and 2011, according to the budget report.

Total savings from the last BRAC were $15.4 billion over the same period, the report says.

The GAO has also reported that with the higher costs, the 2005 BRAC round will not break even until 2018.