WASHINGTON, Oct 27 (Reuters) Barack Obama, struggling to gain ground on rival Hillary Clinton in the 2008 White House race, faces a delicate dilemma in trying to bring down the Democratic front-runner without spoiling his upbeat image.
After launching his campaign with a burst of excitement, the first-term Illinois senator is mired more than 20 points behind Clinton in national polls and trails by smaller margins in the early voting states of Iowa and New Hampshire barely two months before the first contests.
While that is plenty of time to turn around the race, Obama's promise of a new style of consensus-building politics has raised questions about how hard-nosed he will be -- or can afford to be -- in confronting Clinton.
''The campaign has to develop a level of aggressiveness and intensity that I'm not sure we've seen yet. If he's playing to win, they are going to have to ratchet it up,'' said Simon Rosenberg, head of the Democratic advocacy group NDN.
But an approach that is too harsh could dilute his message, alienate his newest converts and harm a potentially bright future in the Democratic Party at the age of 46, analysts said.
''Obama is in a tough spot. He has to be very careful about how he handles himself from here on forward,'' said Democratic consultant Dane Strother. ''He can't turn himself into just another politician. His entire attraction is that he is different.'' Obama has stepped up his criticism of Clinton in the last few weeks, more directly questioning the New York senator's 2002 vote to authorize war in Iraq and comparing it to his early opposition to the conflict.
Along with many of the other contenders to be the Democratic nominee in the November 2008 election, he also criticized her recent vote endorsing the possible labeling of an Iranian military force as a terrorist group.
''We're going to make clear what the policy differences are between us and Hillary Clinton. Voters expect that and Democrats deserve that,'' Obama spokesman Bill Burton said.
NO MORE 'SLASH-AND-BURN' ''We don't think Americans are looking for slash-and-burn politics and the same old divisiveness,'' Burton said. ''Barack Obama has set a higher standard for this campaign and we consider that to be refreshing to voters, not a liability.'' Obama, who would be the first black president in US history, has stirred enthusiasm among grass-roots Democratic activists. He leads the primary fund-raising chase and attracts big crowds on the campaign trail even as he slips farther behind establishment favorite Clinton in national polls.
Part of his problem, analysts say, has been the high expectations and heavy publicity he has generated since he excited Democrats with his keynote speech at the 2004 nominating convention.
''In many ways he is running an insurgent campaign, but he was very big, very quickly. Most insurgent campaigns take longer to grow,'' said Dante Scala, a political analyst at the University of New Hampshire. ''Voters here like a scrappy underdog, and he never fit that role.'' Obama's campaign dismisses the national polls as exercises in name recognition, pointing out Obama, Clinton and rival John Edwards are in a tight three-way race in Iowa, where an early win can immediately change the dynamics of the race.
''I don't think he needs to differentiate himself from Clinton any more, although he certainly can on things like the Iraq war vote,'' said Gordon Fischer, former chairman of the Iowa Democratic Party and an Obama supporter.
What Obama needs to do now, he said, is ''organize, organize, organize. Iowa is a three-way scramble right now, and Obama's strength is going to be his organization.'' Edwards, who finished second to John Kerry in the 2004 Iowa presidential contest before becoming his vice presidential running mate, has been far more aggressive in attacking Clinton on the campaign trail.
''Obama can allow Edwards and the rest to take Hillary on. He doesn't have to carry the load,'' Strother said. ''He has the freedom to stay above the fray.'' REUTERS LPB KN0848