The murder by Islamist terrorists of Ambassador J. Christopher Stevens and three other Americans in Libya on the anniversary of the Sept. 11 attacks has become one of the most contentious issues in the election. The administration has been flailing around, unsure of its facts, offering statements that turned out to be misleading. Republicans, led by Senator John McCain, have jumped on the errors by the State Department and the CIA that contributed to the confusion over our understanding of the slaughter in Benghazi, and backed an unrelenting press campaign attempting to show Barack Obama as either incompetent, a liar, or both.

Yet, despite six weeks of heavy pounding on Obama’s approach to terrorism and national security, an issue that in the past has occupied Americans as a top priority, the president’s reputation remains largely unscathed and, according to polls, voters still consider him more suited than Mitt Romney to run America’s foreign and security policies. Why has such a virulent campaign to discredit Obama’s record as commander-in-chief so conspicuously failed?

When John McCain first commented on the death of his friend Ambassador Stevens, he was careful with his words. After a wild accusation by Mitt Romney condemning the U.S. embassy in Cairo for blaming anti-western mob violence across the Arab world on a video that made fun of the prophet Mohammad, the senator from Arizona was reluctant to apportion blame for the American deaths. Asked on Sept. 13 about the administration’s response to the killings, he said: “I think it was fine. By the way, Secretary of State Clinton gave a marvelous statement today.” By last weekend, however, he was accusing the administration of “either cover-up or gross — the worst kind of incompetence, which doesn’t qualify the president as commander in chief.”

In the intervening six weeks there has been a dogged attempt to determine exactly who killed the ambassador and his men and why the administration at first gave the impression it was part of a general demonstration against the blasphemous video, but later under pressure conceded it was a carefully planned and poignant Sept. 11 attack by Islamists. Leading the charge against the president’s competence is Rupert Murdoch’s Fox News and New York Post, though CNN has also persistently questioned what went wrong in Benghazi, at the State Department, and at Langley.

Despite the campaign of denigration, a month after the murders voters were evenly split on whether they approved of the president’s handling of the attack, with opinions divided almost entirely on party grounds. Independents tilted slightly towards disapproval. Poll evidence suggests that on the Benghazi attack Fox has been preaching to the choir. While Republicans have taken a keen interest in learning the details, Democrats are not engaged, and Independents remain split. More significantly, surveys show that despite attempts to lay the Benghazi deaths at Obama’s door, since Sept. 11 there has been no shift in the numbers saying they prefer Obama to Romney when it comes to foreign affairs and national security. And Obama still has a significant lead when it comes to who voters trust to counter terrorism and who they would prefer to lead them into a crisis.