An obscure word played for laughs from a mostly white crowd at the expense of a man of Indian descent clouds what has been a bright political career for Sen. George Allen, including any White House plans.

The Republican, seeking a second term as he explores a 2008 presidential run, apologized directly Wednesday to the Democratic aide he targeted, then joined President Bush for a private fundraiser in the Virginia suburbs of Washington.

But the damage has been done and it will haunt Allen for a while, said Merle Black, a political scientist at Emory University in Atlanta and a specialist in presidential and congressional races.

"Clearly this has damaged his presidential aspirations," Black said in a telephone interview. "It just raises questions about his judgment and how sincere he is in how he deals with these kinds of issues."

At an Aug. 11 rally with about 100 supporters at Breaks, Va., near the Kentucky border, Allen singled out S.R. Sidarth, a volunteer who was tracking Allen and videotaping his campaign events for Democrat Jim Webb, and twice called him "Macaca."

"Let's give a welcome to Macaca here. Welcome to America and the real world of Virginia," Allen said over laughter and ovations to Sidarth, a 20-year-old of Indian ancestry who was born in Fairfax County.

Macaca is a genus of monkeys including macaques. The name also could be spelled Makaka, which is a city in South Africa. Sidarth said he felt Allen tried to single him out by race.

Sidarth recorded Allen, Webb's campaign posted the video on YouTube, and then the campaign alerted reporters. Within days, it became the dominant political story on network and cable news programs. Perhaps more damaging, it became grist for late-night talk shows and Comedy Central's "The Daily Show," with Jon Stewart.

"In politics, when you become fodder for David Letterman and Jay Leno and Jon Stewart, you know you've had a bad day," said Tom Rath, a Republican National Committee member from New Hampshire.

To remain a strong presidential contender, Allen needs to beat Webb convincingly, and that job has become much tougher, Black said. "If it's close, that would be a sign of weakness and it will not help him in a national race," he said.

Allen's Senate candidacy alone has kept him from visiting the crucial early voting states — Iowa and New Hampshire — that potential GOP rivals John McCain, Rudy Giuliani, Mitt Romney and others are touring this year.

And wherever Allen goes, Black said, the video will be hard for Allen to shake because it shows him pointing to Sidarth and singling him out for derision, and because he smiled as he needled Sidarth, seemingly enjoying the moment.

"He was giving no consideration to how this event would look if it went on TV," Black said.

Allen tracked Sidarth down Wednesday at the University of Virginia where he had returned for senior year of classes and apologized to him personally, said campaign manager Dick Wadhams.

"Senator Allen made a heartfelt apology. He told Sidarth he thought he would see him on the campaign trail, but Sidarth had headed back to U.Va., so we Googled his name, found his number and the senator called him this morning," Wadhams said.

GOP strategists agreed that Allen has damaged himself, but the incident need not doom him politically.

"Senator Allen needs to make it clear that he made a mistake, that this was obviously something he should not have done," said Mike Mahaffey, a former Iowa Republican Party chairman.

Iowa's nominating caucuses rely on one-to-one politics, giving Allen a chance to personally appeal to voters and convince them the incident was an aberration.

"If he can come across as sincere in that regard, it will not hamper him in Iowa," said Mahaffey, a GOP activist with a law practice in Montezuma, Iowa.

Rath said Allen's conservative credentials and his personal charm can appeal to New Hampshire Republicans if they get to know him. But because the Senate race keeps Allen in Virginia, Rath said, he remains "sort of the man behind the curtain here."

"To suddenly come back in this context is probably not the way he would have designed it," Rath said. "But I don't think it's fatal to him and a lot of Republicans here are very interested in taking a good hard look at George Allen."