Former US President Jimmy Carter says much of the vitriol against President Barack Obama's health reforms and spending plans is "based on racism", reported BBC.
Mr Carter told a public meeting there was "an inherent feeling among many in this country that an African-American should not be president".
Republican lawmaker Joe Wilson was rebuked on Tuesday in a House vote.
He shouted "You lie!" while Mr Obama was delivering an address on healthcare to Congress last Wednesday.
The House resolution of disapproval described it as "a breach of decorum".
But Mr Wilson's eldest son, Alan, has denied racism was a factor in his father's outburst.
Some conservatives have accused the president's supporters of playing the race card.
Angry town hall meetings and a recent taxpayers' demonstration in Washington have been vitriolic towards the president, reports the BBC's North America editor Mark Mardell.
Many have not just protested against the president's policies but have accused him of tyranny, and have promised to "reclaim America".
"Those kind of things are not just casual outcomes of a sincere debate on whether we should have a national programme on healthcare," Mr Carter said at a public meeting at his Carter Center in Atlanta held prior to the Congress vote on Tuesday.
"It's deeper than that."
Responding to a question specifically on Mr Wilson's outburst, he said Mr Obama was the head of state as well as the head of government and - like heads of state elsewhere, such as the Queen of England - he should be "treated with respect".
It was a "dastardly thing to do", he said.
His comments were rejected by Joe Wilson's son, Alan, an Iraq veteran who is running for state attorney general in Georgia.
"There is not a racist bone in my dad's body," he said.
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