"Black voters shouldn't blame Senator Clinton for running a vigorous campaign against me," the Illinois senator told reporters after a rally in this heavily African-American community.
"That should be a source of pride," he said. "It means I might win this thing."
But Obama did not apologize for a radio ad here that says, "Hillary Clinton will say anything to get elected."
He said it responds to a Clinton ad that repeats a "discredited" claim that Obama praised Ronald Reagan's policies. Obama says he was simply noting the former Republican president's influence and political success.
If people including the Clintons "are making false assertions," he said, he will aggressively set the record straight.
As for the campaign's overall tone, Obama said, "I don't feel like the candidates are getting bloodied up. This is good practice for me, so when I take on those Republicans I'll be accustomed to it."
His comments followed a day of sometimes bitter remarks from the campaigns and former president Bill Clinton, who has stumped for his wife all week in South Carolina.
Clinton on Wednesday said Obama and the news media had stirred up tensions over race in response to some Democrats' criticisms of the couple's strategies.
"I never heard a word of public complaint when Mr. Obama said Hillary was not truthful," and had "no character, was poll-driven. He had more pollsters than she did," the ex-president said in a heated exchange with a CNN reporter. "When he put out a hit job on me at the same time he called her the senator from Punjab, I never said a word."
Neither Clinton nor his wife said what he meant by "hit job."
The former president has accused Obama of exaggerating his anti-war record and handing out undeserved praise to Republicans. He said the Obama campaign has manipulated the news media, telling the CNN reporter, "shame on you."
Last year, Obama's campaign circulated a memo describing Hillary Clinton as "D-Punjab," a reference to her Indian-American donors. Obama has said it was a mistake made by an aide.
Bill Clinton this week also suggested that his wife may lose Saturday's primary because many black voters will side with Obama. The unusually direct comment on the possible role of race in the election was in keeping with the Clintons' bid to portray Obama as the clear favorite, thereby lessening the potential fallout if it proves true.
Voting for president along racial and gender lines "is understandable, because people are proud when someone who they identify with emerges for the first time," the former president told a Charleston audience.
Obama, speaking Thursday at a rally of about 800 people in Kingstree, omitted some, but not all, of the jibes he usually aims at Hillary Clinton in his stump speech. He still poked fun at her for saying she voted for a 2001 bankruptcy bill but was happy when it failed to become law.
(Copyright 2008 by The Associated Press. All Rights Reserved.)