The oddity of the Republican response to what happened in Benghazi is partly this focus on half-baked conspiracy theories rather than on the real evidence of failures by the State Department, Pentagon and CIA in protecting the Benghazi mission. What’s even stranger is the singling out of Ms. Rice, a Rhodes scholar and seasoned policymaker who, whatever her failings, is no one’s fool.

Could it be, as members of the Congressional Black Caucus are charging, that the signatories of the letter are targeting Ms. Rice because she is an African American woman? The signatories deny that, and we can’t know their hearts. What we do know is that more than 80 of the signatories are white males, and nearly half are from states of the former Confederacy. You’d think that before launching their broadside, members of Congress would have taken care not to propagate any falsehoods of their own.