Senator Barack Obama is a man of few rhetorical stumbles, but this week a few of his words opened a racial door his campaign would prefer not to step through. When Senator John McCain’s camp replied by accusing him of playing the race card from the bottom of the deck, the Obama campaign seemed at least momentarily off balance.

The instinctive urge to punch back was tempered by the fact that race is a fire that could singe both candidates. So on Friday the Obama campaign, a carefully controlled lot on the best of days, reacted most cautiously as it sought to tamp down any sense that it was at war with Mr. McCain over who was the first to inject race into the contest. Mr. Obama made no mention of the issue, except for a brief reference in an interview with a local newspaper in Florida.

“I was in Union, Mo., which is 98 percent white, a rural conservative, and what I said was what I think everyone knows, which is that I don’t look like I came out of central casting when it comes to presidential candidates,” he told The St. Petersburg Times. “There was nobody there who thought at all that I was trying to inject race in this.”

The furor started on Thursday when Rick Davis, Mr. McCain’s campaign manager, said, “Barack Obama has played the race card, and he played it from the bottom of the deck.” Mr. Davis was alluding to Mr. Obama’s remarks on Wednesday that Republicans would try to scare voters by pointing out that he “doesn’t look like all those other presidents on the dollar bills.”