In an interview he gave to the New York Observer, a weekly newspaper, Biden described Obama as “the first mainstream African American (presidential candidate) who is articulate and bright and clean and a nice-looking guy. I mean, that’s a storybook, man.”

Asked during a conference call with reporters to explain his choice of words, Biden said he meant no offence in describing Obama the way he did, then lavished praise on the Illinois senator as a “very special guy” who has caught “lightning in a jar” like no politician he has seen before. “This guy is a superstar,” he added.

Obama later issued a statement that absolved Biden only in part. “I didn’t take Senator Biden’s comments personally,” he said, “but obviously they were historically inaccurate. African-American presidential candidates like Jesse Jackson, Shirley Chisholm, Carol Moseley Braun and Al Sharpton gave a voice to many important issues through their campaigns, and no one would call them inarticulate.”

After Obama’s statement, Biden issued a statement further backtracking. “I deeply regret any offence my remark in the New York Observer might have caused anyone,” he said.

It was the second time in months that Biden has been forced to explain a comment that some interpreted as racially insensitive. In a videotaped exchange with a supporter last June, he said, “You cannot go to a 7-Eleven or a Dunkin’ Donuts (in Delaware) unless you have a slight Indian accent. I’m not joking.”

In the Observer interview and in a television interview, Biden also criticised Senator Hillary Rodham Clinton’s proposal to cut funding to Iraqi security forces. “I think it would be a disaster, if that is her plan,” he said of the New York senator on “Good Morning America.” “They’re the people we’re supposed to be training so that we can rely on them to aid us in the efforts that we undertake.”

Biden called Clinton “clearly qualified” to be president but told the Observer the fact that so many Democrats do not support her gave him hope that he could win the nomination. “My point was she’s known by 100 per cent of the people and has had the legitimate and understandable support from her husband and there are still 60 per cent of the people up for grabs,” he told reporters.

Biden also was critical of another presidential rival, former North Carolina senator John Edwards. “I don’t think John Edwards knows what the heck he is talking about” on Iraq, he said.

Biden said he believes he has the unique set of attributes to get US out of Iraq without further damaging US interests around the world. “The next president of the United States, because of the policies of this president, is going to have no margin for error,” he said on ABC.