Sen. Barack Obama (D-Ill.) on Friday afternoon seized the superdelegate lead from Sen. Hillary Rodham Clinton (D-N.Y.), giving him command of every aspect of his party’s presidential nomination race. That constitutes a key milestone in the race and a shocking reversal of fortune for Clinton. Obama once was behind by more than 100 superdelegates. But according to at least two counts, more superdelegates are now in his camp. Politico’s tally now shows him ahead of her by 270 superdelegates to 268.5, with 208.5 uncommitted. (Superdelegates from U.S. territories count as one-half.) ABC News shows him ahead by two. Clinton’s longtime...