The debate started with foreign policy, a topic absent from the presidential debate last week.

Rep. Paul Ryan accused Vice President Biden tonight – and by extension President Obama – of failing to candidly acknowledge the facts surrounding the recent deadly attack on the U.S. diplomatic in Libya.

The Sept. 11 strike on the U.S. consulate in Benghazi, Libya, which killed U.S. Ambassador J. Christopher Stevens and three other Americans, has exposed the Obama administration in the campaign’s stretch run on an issue (national security) it considers a political strength.

The attack, connected to the al Qaeda affiliate in North Africa, was bad enough. But the administration’s changing explanation for what happened that day – a spontaneous protest or a coordinated attack on a thinly protected U.S. mission? – has drawn Republican accusations of a White House cover-up to avoid a politically damaging acknowledgement of a terrorist strike.

“It took the president two weeks to acknowledge this was a terrorist attack,” Ryan said. “If we are hit by terrorists we’re going to call it what it is: A terrorist attack.”

Ryan said the administration failed to adequately protect the mission. Biden shot back that Ryan cut funds for embassy security in his budget proposal.

Mitt Romney has also struggled with the issue after coming out with a sharp attack on Obama before all the facts of the attack had been compiled, even drawing criticism from some Republicans for doing so.

However, as Congress digs into the event, the administration remains on the defensive, as Ryan sought to emphasize tonight.

“We will find and bring to justice the men who did this,” Biden said. “Whatever mistakes were made will not be made again.”

Romney brought up the Libya attack earlier Thursday, saying "the American people wonder why it took so long for your administration to admit that this was a terrorist attack.””