US:Republican and Democratic presidential candidates face a gruelling 72 hours of campaigning across the United States ahead of Super Tuesday, when more than 20 states hold primaries and caucuses.
With polls showing Barack Obama closing in on Hillary Clinton, both Democratic candidates campaigned yesterday in California, the biggest prize next Tuesday with one fifth of the total number of delegates needed to win the nomination.
On the Republican side, John McCain is surging ahead of his closest rival, Mitt Romney, with Mike Huckabee and Ron Paul trailing far behind. "I give him a slight edge, but it's a two man race now," Mr Romney said of Mr McCain yesterday.
Mr Obama yesterday won the endorsement of California's Service Employees' Union, which had earlier endorsed John Edwards and later won the support of the liberal advocacy group MoveOn.org.
Mr Obama said in Los Angeles yesterday he was confident that, if he becomes the Democratic nominee, he will win the votes of Ms Clinton's supporters but that he was not sure if all of his supporters would vote for her.
Ms Clinton and Mr Obama appeared before a star-studded audience at Hollywood's Kodak Theatre on Thursday night for a debate that saw none of the verbal fireworks of earlier encounters. Instead, the two remaining candidates were all smiles, whispering and almost embracing one another as they shared a private joke at the end.
"I was friends with Hillary Clinton before we started this campaign; I will be friends with Hillary Clinton after this campaign is over," Mr Obama said.
There were almost as many stars at the Kodak Theatre on Thursday as when it hosts the annual Academy Awards ceremony, including actors Leonardo di Caprio, Diane Keaton and Pierce Brosnan and directors Stephen Spielberg, Rob Reiner and Quentin Tarantino.
Ms Clinton appeared more in command during the first half of the debate, which focused on domestic issues, as she pointed out distinctions between her healthcare plan and Mr Obama's. Asked about the impact of illegal immigration on job prospects for African-Americans, Mr Obama said that immigrants should not be used as scapegoats but Ms Clinton said that such concerns were legitimate.
"I believe that in many parts of our country, because of employers who exploit undocumented workers and drive down wages, there are job losses. And I think we should be honest about that. There are people who have been pushed out of jobs and factories and meat processing plants, and all kinds of settings," she said before calling for comprehensive immigration reform.
Ms Clinton had one of the most popular lines of the night, in response to a question about the role of former president Bill Clinton if she returns to the White House. "It did take a Clinton to clean up after the first Bush and I think it might take another one to clean up after the second Bush," she said.
Ms Clinton moved onto the defensive, however, when she was questioned about her 2002 vote to authorise the war in Iraq, a vote she refused to characterise as a mistake, although she said that president Bush misused the authority granted by Congress.
In the Republican race, Mr Romney has stepped up his attacks on Mr McCain, complaining that the Arizona senator used tactics that were "reminiscent of the Nixon era" in questioning his record on the Iraq war. "I don't think I want to see our party go back to that kind of campaigning," Mr Romney said.
Mr Romney has the support of many conservative pundits and radio talk show hosts, some of whom have said they dislike Mr McCain so much that they would prefer to vote for Ms Clinton.
Campaigning in Oklahoma, Mr Huckabee poked fun at Mr Romney as "a man who didn't hit political puberty in the conservative ranks until he was 60 years old" as he catalogued the former Massachusetts governor's shifting positions on hot-button conservative issues.
"I just think you can't just have a change of opinion on fundamental issues over and over and wait until you're running for president to do it," Mr Huckabee said.