Obama sympathises with Clinton over 'careless' RFK assassination remark

But the Democrat frontrunner also blasted the former First Lady for trying to stir up a controversy over disqualified votes in Florida to boost her fading bid for the party’s White House nomination.

Although she apologised for her Kennedy murder gaffe, the storm it generated continued throughout the weekend.

Sympathetic: Barack Obama told reporters he understands how his Democrat presidential candidate rival Hillary Clinton came to make her 'careless' remark

Mrs Clinton had been asked why she was continuing her campaign into next month. She replied that her husband, former President Bill Clinton, didn’t wrap up his nomination until June in 1992, and added: ‘We all remember Bobby Kennedy was assassinated in June in California.’

Kennedy, brother of slain U.S. President John F. Kennedy and Massachusetts Sen. Edward Kennedy, was assassinated during his 1968 race for the Democratic presidential nomination.

Some interpreted Mrs Clinton's remark as hinting she was staying in the contest because of a possibility of Obama being assassinated. She immediately insisted she had purely been making a statement of historic fact in support of her continuing.

Hillary Clinton has apologised after citing RFK's June assassination as a reason for staying in the presidential race

The comment touched a particularly raw nerve with the Obama camp anxious about the Illinois senator’s safety in his historic attempt to become America’s first  black president. He was given secret service protection 18 months before November’s presidential election – earlier than any other candidate.

But Mr Obama, 46, said he did not take any offence.

‘I have learned that when you are campaigning for as many months as Senator  Clinton and I have been campaigning, sometimes you get careless in terms of the  statements that you make, and I think that is what happened here,’ he said in Puerto Rico, where Democrat voters go to the polls next weekend.

Robert Kennedy, pictured in 1960 during his brother John's election campaign

Robert Kennedy Jr., son of the slain senator, said in a statement, "It is clear from the context that Hillary was invoking a familiar political circumstance in order to support her decision to stay in the race through June."

"I understand how highly charged the atmosphere is, but I think it is a mistake for people to take offence," said Kennedy, a Clinton supporter unlike some other members of his family, including Sen. Edward Kennedy, who back Obama.

Meanwhile, former U.S. President Jimmy Carter today hinted strongly that he would be backing Obama, saying he and other Democratic superdelegates will reveal their choice for presidential nominee soon after the final primary in June and that Hillary Clinton will then have to quit the race.

Former U.S. President Jimmy Carter has strongly hinted he will back Barack Obama and not Hillary Clinton

Carter said he did not think Clinton was achieving anything by staying in the fight.

'I think not. But of course she has the perfect right to do so," he said while attending the Hay literary festival in Britain.

'I'm a superdelegate ... I think a lot of the superdelegates will make a decision quite rapidly, after the final primary on June 3.

'I have not yet announced publicly, but I think at that point it will be time for her to give it up.'

Obama has an almost insurmountable lead over Clinton in the race for the Democratic nomination. The former first lady has said she would continue until the last state has held its nominating contest.