President Barack Obama says he loves Sen. Arlen Specter (D-Pa.) — just not quite enough to hazard an 11th-hour political trip to Pennsylvania for an ally of convenience increasingly viewed as unlikely to win. Just last year, the White House was crowing about Specter’s conversion to the Democratic Party, and Obama pledged, “He will have my full support. . .” Tuesday’s primary is telling a different story: Once thought to be an unalloyed asset for most any Democratic candidate, Obama’s personal involvement is no longer guaranteed – or guaranteed to succeed. In close to a dozen contests, Obama’s intervention hasn’t...