In the autumn of 2008, Colin Powell, the former Secretary of State under George W. Bush, broke from the Republican Party and endorsed the Democratic nominee for President, Barack Obama. It had been a brutal summer of electoral warfare. Rumors that Obama was Muslim swirled, becoming a significant aspect of the media coverage of his campaign. A group working with his opponent, John McCain, called people in swing states, planted doubts about Obama’s religious background, and asked how they would vote if they knew that the Democrat was supported by Hamas. McCain’s spokesperson defended the calls, but when a voter...