The race for the White House has narrowed dramatically with the withdrawal of Democrat John Edwards and former Republican frontrunner Rudy Giuliani.
Mr Giuliani yesterday planned to endorse Arizona senator John McCain, who won Tuesday's Republican primary in Florida to become his party's frontrunner ahead of Super Tuesday next week.
Mr Edwards's withdrawal leaves Hillary Clinton and Barack Obama as the only remaining Democratic candidates in a closely fought contest that could continue right up to the party's convention in August.
Mr Edwards returned to New Orleans, where he launched his presidential bid 13 months ago, to declare that it was time for him to step aside after coming third in all but one of the Democratic primaries and caucuses so far.
He said both Mrs Clinton and Mr Obama had promised to make his main theme of ending poverty central to their campaigns for the presidency.
"With our convictions and a little backbone, we will take back the White House in November."
Mr Edwards said he would meet both candidates before deciding if he should endorse either of them, and both Mrs Clinton and Mr Obama praised their former rival.
"John Edwards ended his campaign today in the same way he started it - by standing with the people who are too often left behind and nearly always left out of our national debate," Mrs Clinton said.
Mr Obama said Mr Edwards shared his view that America's divisions could be overcome, and that the country could rally around a common purpose.
"So while his campaign may have ended, this cause lives on for all of us who still believe that we can achieve that dream of one America," Mr Obama said.
Four candidates remain in the Republican race, but only former Massachusetts governor Mitt Romney represents a real challenge to Mr McCain for the nomination.
Mr Romney, who has spent an estimated $40 million (€27 million)from his personal fortune on his campaign so far, is presenting himself as a more conservative alternative to the maverick Mr McCain.
Mr McCain won 36 per cent of the vote in Florida compared to Mr Romney's 31 per cent, leaving Mr Giuliani trailing in third place with 15 per cent.
His party's frontrunner for much of last year, Mr Giuliani ignored most of the early contests to focus on Florida and the big states that vote next week.
However, while the former New York mayor was out of the headlines, Mr McCain's campaign recovered from near-extinction, and Mr Romney's vastly superior spending power ensured that he remained a powerful contender.