Two weeks after President Obama said that Cambridge, Mass., police had “acted stupidly” by arresting Harvard University Prof. Henry Louis Gates for arguing with them inside his home, Republicans are still taking stock of their unexpected political gift. A Pew Research poll released on July 30 found the president’s approval rating among white voters slipping seven points, from 53 percent to 46 percent, explicitly because of their disappointment in the Gates remarks. A CNN/Opinion Research poll released on August 4 found that six out of 10 white voters disagreed with the president’s remarks. A Quinnipiac poll released on August 6...