Video and comment: Clinton gaffe | Video: Huckabee: 'you will see the gates of Hell'

A race row has erupted between Barack Obama and Hillary Clinton, over a comment that the former First Lady made about Martin Luther King.

In South Carolina, scene of a key showdown on January 26, where half the Democratic electorate are African Americans, black radio hosts have expressed outrage over Mrs Clinton’s remark. Now one of the state’s most influential black congressmen is hinting that he might endorse Mr Obama.

He said he was angered by what he claims were dismissive comments about Martin Luther King by Mrs Clinton. Aides to Mr Obama, who hopes to become America’s first black president, are also accusing Bill Clinton of being racially insensitive when he said in New Hampshire last week that Mr Obama’s campaign was a “fairytale”.

James Clyburn, the highest-ranking African American in Congress and a veteran of the civil rights movement, referred to a comment made by Mrs Clinton on Monday, the day before her stunning comeback in New Hampshire set up a brutal nomination battle with Mr Obama.

Mrs Clinton, trying to make a point about presidential leadership and Mr Obama’s constant references to Dr King, the civil rights icon, said: “Dr King’s dream began to be realised when President Lyndon Johnson passed the Civil Rights Act of 1964. It took a president to get it done.”

Mrs Clinton has since tried to clarify the comment, but the damage was done. Mr Clyburn, who had previously said that he would stay neutral, told The New York Times that he had been “bothered a great deal” by the remarks and was rethinking his position.

The Republicans, meanwhile, face their own showdown in the South Carolina primary next Saturday, a contest that could prove critical to the race, and where conservative evangelicals hold significant sway among the primary electorate. In a debate on Thursday, Mike Huckabee, the former Arkansas governor and former Baptist minister, sought to appeal to the Religious Right. Victory in the Palmetto State would confirm his status as a serious contender after his victory in Iowa.

He has faced grave doubts about his foreign policy experience, his greatest vulnerability, but got one of the biggest cheers of the night when asked about the incident last week when Iranian boats swarmed US navy ships in the Strait of Hormuz.

Asked whether the US commanders were right in not attacking the Iranian boats, Mr Huckabee said that he backed their decisions, before warning Iran: “Be prepared, first, to put your sights on the American vessel. And then be prepared that the next thing you see will be the gates of Hell.”

The Republican contenders Mitt Romney and John McCain do battle on Tuesday in Michigan’s primary. Defeat for Mr Romney would probably kill off his campaign after his defeats in Iowa and New Hampshire. Mr McCain, now leading in Michigan and South Carolina, badly needs victory on Tuesday to keep his comeback on track after his big win in New Hampshire.

The next Democratic contest is on Saturday, in Nevada, where Mrs Clinton and Mr Obama are fighting for the Hispanic vote. Janet Napolitano, the Arizona governor, plans to endorse Mr Obama, backing that could help him in neighbouring Nevada and in her own state when it votes on February 5, one of more than 20 going to polls on “Super Tuesday”.

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