US Secretary of State Hillary Clinton says she takes responsibility for the failure in security at the US consulate in Benghazi, where the US ambassador to Libya was killed last month. Mrs Clinton said ensuring the safety of US diplomatic staff overseas was her job, not that of the White House. It comes ahead of the second campaign debate between President Barack Obama and Republican candidate Mitt Romney. In all, four Americans died when the US consulate in Benghazi was attacked. "What we had to do in the state department was keep focused not on why something happened - that was for the intelligence community to determine - but what was happening and what could happen," she told US TV channels. "And that's what I was very much working on, day and night, to try to make sure that we intervened with governments. We did everything we could to keep our people safe, which is my primary responsibility." The Obama administration has faced withering criticism over the attack on the Benghazi consulate. Republicans are heaping blame on the administration - and specifically on the White House itself, says the BBC's Adam Brookes in Washington. In interviews, Mrs Clinton appeared to acknowledge that she was trying to shield the president, our correspondent says. With the next debate between Mr Obama and his Republican challenger, Mitt Romney, only hours away, it seems Mrs Clinton is trying to draw criticism away from Mr Obama, who needs a strong debate performance if he is to recover his lead in the polls, he adds. Mrs Clinton said she was focused on tracking down the killers of the US ambassador to Libya and bringing them to justice. "I don't think we want to get into any blame game. I think what we want to do is get to the bottom of what happened, figure out what we're going to do to protect people and prevent it from happening again and then track down whoever did and bring them to justice." Mr Obama and Mr Romney are preparing to face off in their second debate later on Tuesday, at Hofstra University in Hempstead, New York. Mr Romney was widely acknowledged as having the upper hand in the first debate, which was reflected in the opinion polls, with many showing for the first time in the campaign Mr Romney in the lead. Earlier this week, the father of the late US ambassador, Chris Stevens, said it would be "abhorrent" to turn his son's death into a campaign issue. "Our position is it would be a real shame if this were politicised," Jan Stevens said.