In a "scathing" new campaign commercial, Sen. John McCain takes his primary opponent J.D. Hayworth to task for his fuzzy understanding of U.S. history, calling the former Congressman one of America's "dumbest" politicians. The vintage newsreel-style ad features Hayworth's recent proclamation that, "The war that Dwight Eisenhower led in Europe against the Third Reich was never declared by the United States Congress." In fact, as the ad crisply points out, the U.S. declared war against Germany in December 1941, under President Franklin D. Roosevelt. Hayworth quickly shot back, accusing McCain of "shamelessly" using his error to distract from "real issues." Hayworth was obviously wrong, says Sean J. Miller in The Hill. But "with the primary still months away... this is unlikely to linger as an issue." Regardless, says Glynnis MacNicol in Mediaite, at least now we know that McCain can be "intentionally funny." Watch the ad: