Amid a trickle of campaign reactions, Obama responded with a written statement midday, calling Palin’s nomination “yet another sign that old barriers are falling in our politics.” He addressed the TV cameras during an afternoon stop at a biodiesel plant and later released details of his congratulatory phone call to Palin.

“He told her she would be a terrific candidate and that he looked forward to seeing her on the campaign trail,” Obama senior strategist Robert Gibbs said. “He also wished her good luck but not too much luck.”

The Obama campaign wasn’t as charitable a few hours earlier, when a spokesman issued a statement blasting McCain for putting a “former mayor of a town with 9,000, with zero foreign policy experience, a heartbeat away from the presidency.”

At his afternoon stop, Obama distanced himself from the first, harshly critical remarks.

“I think that, uh, you know, campaigns start getting these, uh, hair triggers and, uh, the statement that Joe and I put out reflects our sentiments,” he said, apparently criticizing his staff for going overboard, as he did occasionally in the primary.

The inconsistent messaging underscored the search among Democrats for the right tone in a presidential race jolted by the sudden addition of a female vice presidential candidate.