Republicans unmoved by Clinton's contrition on Libya

Clinton's statement is being perceived as an effort to shield Obama from attacks on his leadership on national-security issues three weeks before Election Day. The issue is almost certain to come up during Tuesday night's second presidential debate.

The administration has come under fire for its shifting explanation of what happened on Sept. 11 and for the State Department's refusal to approve the U.S. Consulate's request for additional security. 

Vice President Biden, during last week's debate with Mitt Romney's running mate, Rep. Paul RyanPaul Davis RyanMcConnell: 'Whoever gets to 60 wins' on immigration Overnight Defense: Latest on spending fight - House passes stopgap with defense money while Senate nears two-year budget deal | Pentagon planning military parade for Trump | Afghan war will cost B in 2018 House passes stopgap spending measure with defense money MORE (R-Wis.), said that he and the president were not aware of the request from Tripoli.

“The president and the vice president wouldn't be knowledgeable about specific decisions that are made by security professionals,” Clinton said Monday. 

“They're the ones who weigh all of the threats and the risks and the needs and make a considered decision.”

The three Republican senators said that doesn't explain reports of numerous security threats prior to the attack on the Benghazi consulate that killed Ambassador Christopher Stevens and three others. 

Many of those threats came to light during a probe of security violations by House Oversight Committee Chairman Darrell Issa (R-Calif.) during a hearing last week.

“If the president was truly not aware of this rising threat level in Benghazi, then we have lost confidence in his national-security team, whose responsibility it is to keep the president informed," the GOP senators write. "But if the president was aware of these earlier attacks in Benghazi prior to the events of Sept. 11, 2012, then he bears full responsibility for any security failures that occurred. The security of Americans serving our nation everywhere in the world is ultimately the job of the commander in chief. The buck stops there.”

During the 2008 presidential campaign, BuzzFeed points out, Clinton herself made that point while sparring with Obama over his stated desire to offer a vision rather than making sure “everything's running on time.”

"I know that we can get on top of this, but it's going to require strong presidential leadership — it's going to require a president who knows from day one you have to run a government and manage the economy," Clinton said then. "The buck stops in the Oval Office."