Rep. Roy Blunt, the GOP candidate in Missouri's competitive U.S. Senate race, has drawn widespread criticism for using footage of the smoldering wreckage of the World Trade Center on 9/11 in a campaign advertisement. The spot knocks his opponent, Sen. Robin Carnahan, for not opposing the so-called Ground Zero mosque. Blunt's campaign has pulled the ad, but Carnahan is suggesting that Blunt owes the families of 9/11 victims an apology for "exploiting" the tragedy. How bad was Blunt's error? The ad was "stupid" and Blunt was right to pull it, says Dave Weigel at Slate. "But realistically, how long are we going to freak out about a candidate using 9/11 imagery in their campaign material?" The immediate lesson, says Greg Sargeant at The Washington Post, is "that the searing national battle over the Islamic center also carries perils for Republicans. It tempts them to crassly politicize the tragedy in ways that — with the 9/11 wound now reopened — risk searing them, too." Watch the video below: