WASHINGTON -- Lawmakers Wednesday got their first opportunity to grill a key member of the Obama administration about cutting back on border security programs.

Homeland Security Secretary Janet Napolitano defended the 2011 border budget, saying the cuts do not put national security at risk. Nursing a broken ankle from a tennis match, Napolitano first answered questions about cuts to border employees.

The most aggressive line of questioning came from Republican Senator Susan Collins of Maine, who wanted the Secretary to admit that reductions were coming.

"Are you reducing the overall number of border patrol agents by 181?" Collins asked.

Napolitano answered, "Are we making more smart and effective use of the moneys you give to the Border Patrol by reducing and reallocating agents so they're actually along the border? Yes!"

"I think it's great that you're getting people out of headquarters, but I need an answer," Collins said. "Are you reducing the overall level by 181 Border Patrol agents?"

Napolitano explained that certain positions -- like training personnel -- would be cut, and those who retire would not be replaced. She was quick to point out that agents who work along the border would not be laid off.

Then came the questions about the $225 million slashed from the "virtual fence" project: a network of cameras, ground sensors and radar, otherwise known as the Secure Border Initiative or SBInet.

According to the group Taxpayers for Common Sense, SBInet has an estimated $6.2 billion price tag with not much to show for it so far.

"This border fence issue has been a waste of billions of dollars," said Arizona Senator John McCain, who asked Napolitano what went wrong.

"Every major deadline has not been satisfied and I am not satisfied with SBInet," Napolitano said.

Napolitano explained that the project didn't fully meet the needs of the Border Patrol and there were logistical problems building the towers along the border.

Nonetheless, she said that SBInet Phase 1 -- a test site in Arizona -- will still be launched this year. The next phase, however, has been cut from the budget pending a major evaluation.

"We need to reevaluate and see if there's other, better, smaller, more mobile, easier to maintain, easier to operate technologies that will pair with our actual boots on the ground in a more effective way," Napolitano said.

McCain has asked the Senate Department of Homeland Security committee to hold a separate hearing on the virtual fence to fully investigate it's progress.

No word yet on when that will take place.