Barack Obama’s campaign for the presidency has revived. Until recently Hillary Clinton had a commanding lead in the polls and was starting to seem unstoppable. But Mr Obama has pulled ahead in Iowa and level in New Hampshire, the states that vote first in the primaries. He is gaining ground again nationally. The television debates, in which he performed poorly, are behind him. What matters now is the ability to move a crowd and the energy of campaign staff on the ground. On the first, Mr Obama has no equal in this contest. On the second, he has no grounds for complaint. He is back in the race.