How is Benghazi attack shaping the 2012 election?

Barack Obama's handling of the terrorist attacks on U.S. diplomatic installations in Benghazi on 9/11 may be giving many voters serious pause this election. With less than 14 days before voters head to the polls, the Wall Street Journal's Daniel Henninger suggests that the president now faces a bit of a credibility gap:

Despite an awful economy, the president's likability numbers held firm. Many wanted to believe in this larger-than-life president. His clumsy handling of Benghazi, however, has opened a gap in the president's credibility. What else can explain Mitt Romney ascending in polls to equality with the president on foreign policy and terrorism before the last debate?

The discomfiture over Benghazi has spilled into other parts of his campaign. Among my top five events of the 2012 election will be that fellow in the town-hall debate who said, "I'm not that optimistic," and asked the president to address what he's doing about "everyday living" in America. He was asking the president he voted for why he should still believe. Mr. Obama diverted into telling him about ending Iraq and killing bin Laden. Instead of presidential assurance, he got talking points.

His weird, persistent vagueness about the shape of a second-term agenda has sown doubt about the economy going forward. Only now is that agenda being revealed, more or less, with a 20-page pamphlet, "The New Economic Patriotism." A new Obama ad urges viewers to "read it."

It may be that voters think both candidates have stretched the truth, but credibility is the coin of a presidency. The political cost of devaluing that coin is higher for an incumbent seeking a second term and higher still for this one. Two weeks from Election Day, Barack Obama has been shown in Benghazi to be a president with feet of clay. It may well take him down.