A war of words with racial undertones marked the White House race on Sunday after civil rights icon John Lewis accused Republican John McCain of sowing “hatred” against Barack Obama.

McCain, who has been trying to tamp down abuse of the Democratic nominee at his campaign events, reacted furiously, lashing out against Lewis, who only a few weeks ago he described as one of the Americans he most admired.

The latest political turbulence came just over three weeks before the Nov 4 election, with Obama building a steady lead over McCain on the national level, and on the state-by-state electoral map.

It also overshadowed another controversy, the legislative probe finding in Alaska that state governor and Republican vice presidential nominee Sarah Palin had abused her power in a feud with her ex-brother-in-law. Congressman Lewis, revered as one of the key figures in the 20th century US civil rights movement, ignited a political firestorm by issuing a statement about McCain’s recent searing character attacks on Obama.

“As public figures with the power to influence and persuade, Senator McCain and Governor Palin are playing with fire, and if they are not careful, that fire will consume us all,” Lewis said. Republicans “are sowing the seeds of hatred and division, and there is no need for this hostility in our political discourse.”

He also appeared to suggest attacks on Obama were reminiscent of late segregationist Alabama governor and presidential candidate George Wallace, whose rhetoric in 1963 was blamed for a church bombing in Birmingham, Alabama, that killed four little girls.

McCain said in his own statement that Lewis had launched a “character attack against Governor Sarah Palin and me that is shocking and beyond the pale.”

He said Lewis’ apparent reference to Wallace was “unacceptable and has no place in this campaign.” McCain called on Obama “to immediately and personally repudiate these outrageous and divisive comments.”

Later, Lewis issued a second statement in an apparent attempt to defuse the row, saying he had not meant to draw a link between Wallace and McCain.

“My statement was a reminder to all Americans that toxic language can lead to destructive behaviour, I am glad that Senator McCain has taken some steps to correct divisive speech at his rallies,” he said.

Chants of “terrorist” and “kill him” were reportedly heard at recent McCain Republican events and some commentators blamed hard-hitting negative advertisements which claimed Obama consorted with a domestic “terrorist” — 1960s radical William Ayers.

On Friday, McCain was forced to intervene twice at a town hall meeting in Minnesota after one voter described Obama as an Arab and another said he was “scared” of the Democratic nominee.

Some political commentators have questioned whether the seething resentment at Republican events could be a security threat or Obama, who was offered Secret Service protection months before is normal for presidential candidates.

Obama campaign spokesman Bill Burton said that the Illinois senator did not believe in the comparison between McCain and Wallace.

But he said Congressman Lewis “was right to condemn some of the hateful rhetoric that John McCain himself personally rebuked.”

Palin earlier denied wrongdoing after a probe found she had abused voters’ trust as Alaska governor.

The legislative investigation found Palin had violated ethics rules by letting husband Todd pressure top officials for the firing of her ex-brother-in-law, a state trooper.

Asked by a reporter in Pennsylvania if the charges were true, Palin replied: “No, and if you read the report you will see that there was nothing unlawful or unethical about it. You have to read the report.”

The report said Palin had “the authority and power to require Mr Palin to cease contacting subordinates, but she failed to act.”

The probe was the latest blow to Palin, who electrified the Republican Party when she was first picked, but has seen her impact, especially among undecided voters and women diminish amid questions about her qualifications.

But with the Democratic nominee steadily gaining in the polls, The New York Times reported Sunday that Republican leaders were worried McCain was heading for defeat unless he brought stability to his presidential candidacy and settled on a clear message.

“You’re starting to feel real frustration because we are running out of time. Our message, the campaign’s message, isn’t connecting,” Saul Anuzis, the Republican chairman in Michigan, was quoted by the paper as saying.

Robert Gleason, the Republican chairman in Pennsylvania, told The Times he was concerned that McCain’s increasingly aggressive tone was not working with moderate voters and women.