The former American president Jimmy Carter says racism and fear is driving the wave of anger directed at Barack Obama as he tries to drive through comprehensive reform of the US healthcare system.

The 84-year-old included in his analysis the heckling of a Republican lawmaker, who shouted out "You lie" at President Obama during his speech to Congress last Wednesday.

“I think that an overwhelming proportion of the intensely-demonstrated animosity toward President Barack Obama is based on the fact that he is a black man, he’s African-American,” Mr Carter told NBC television, in a potentially explosive intervention in national politics.

“I live in the South, and I have seen the South come a long way. But that racism inclination still exists, and I think it has bubbled up to the surface because of a belief among many white people, not just in the South but across the country, that African-Americans are not qualified to lead this great country.

“It is an abominable circumstance, and grieves me and concerns me deeply."

Democrats last night pushed a vote through the House of Representatives reprimanding Joe Wilson, a South Caroline Republican, for heckling Mr Obama. The vote of censure was split 240:170.

Mr Wilson made his outburst as Republicans were murmuring their disapproval after the President said that illegal aliens would be ineligible for federal subsidies to buy health insurance under the system being proposed.

The congressman's Republican colleagues rejected yesterday's vote as a witchhunt, and Mr Wilson, who has already apologised to Mr Obama, insisted that he owed the House no apology.

Mr Carter is not the first to warn that the tide of anger against the Obama administration - especially in the Republican heartland - is rooted in racism.

The Washington Post columnist Colbert King wrote that there was "something loose in the land, an ugliness and hatred directed toward Barack Obama, the nation’s first African American president, that takes the breath away".

In The New York Times, the commentator Maureen Dowd said that Mr Wilson's heckle - and what she said was the unspoken word "You lie, boy!" - showed that Mr Obama was “at the centre of a period of racial turbulence sparked by his ascension”.

“This president is the ultimate civil rights figure -- a black man whose legitimacy is constantly challenged by a loco fringe," she added.

But Mr Obama's opponents say that crying racism was merely a crude attempt to to muffle dissent.

“It is an intimidation tactic. When you make that attack and call someone racist or homophobic it is a way to kind of silence them,” said Brendan Steinhauser, coordinator for FreedomWorks, which organised the first large-scale protest against Mr Obama in Washington at the weekend.

“This movement is made up of people who oppose big government. The idea that people are trying to bring race into this is absolutely ridiculous."

Mr Carter, who served as president from 1977 to 1981, was asked about Mr Wilson's outburst in a meeting at his presidential centre in Atlanta.

"I think it's based on racism," he replied, describing it as part of a disturbing trend directed at the president that has included demonstrators equating Mr Obama to Nazi leaders. “There is an inherent feeling among many in this country that an African-American should not be president.”

Mr Wilson's eldest son defended his father against Mr Carter's attack.

“There is not a racist bone in my dad’s body,” said Alan Wilson, an Iraq veteran who is running for state attorney general. “He doesn’t even laugh at distasteful jokes. I won’t comment on former President Carter, because I don’t know President Carter. But I know my dad, and it’s just not in him.”

He added: “It’s unfortunate people make that jump. People can disagree - and appropriately disagree - on issues of substance, but when they make the jump to race it’s absolutely ludicrous. My brothers and I were raised by our parents to respect everyone regardless of background or race.”

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