The GOP must decide whether to follow the Tea Party over a cliff. Dems must decide whether to distance themselves from Obama. And the president must prove once again that he can tip events in his favor. Republicans, Democrats, and the White House have all reached separate decision points for 2010—and possibly for 2012, as well. Republicans had assumed they were harnessing the energy of the Tea Party movement. Instead, with the ABC/Washington Post poll now registering majority disapproval of the Tea Party, Republicans find themselves in an accelerating march of folly. As a result, they have diminished their moment...