http://news.yahoo.com/s/nm/20070808/ts_nm/usa_politics_democrats_dc By Steve Holland Wed Aug 8, 4:54 PM ET WASHINGTON (Reuters) - Hillary Clinton has surged to a big lead in national polls for the 2008 Democratic presidential nomination but her chief rivals say the polls are overblown and the race is far from over. According to a realclearpolitics.com average of recent polls, the New York senator and former first lady is enjoying a gap of 18 percentage points over her closest challenger, Illinois Sen. Barack Obama, 41 percent to 22 percent, while former North Carolina Sen. John Edwards has 11.5 percent. Democratic strategist Jenny Backus, who is neutral in the 2008 nomination race, said the national polls are important but that Obama and Edwards are making the race a more difficult one for Clinton than her camp had anticipated. "I think Hillary is the front-runner but not the front-runner she thought she was going to be when this race started. She was supposed to be this colossus striding over a field of pygmies. But instead she's in a hand-to-hand battle with one very ferocious competitor and a couple others breathing on her heels," said Backus. Clinton is doing her best to stay above the fray, as she did on Tuesday night in a Democratic debate in Chicago, shrugging off attacks from her rivals and emphasizing the need for unity to defeat the Republicans. "You know, I've noticed in the last few days that a lot of the other campaigns have been using my name a lot. But I'm here because I think we need to change America. And it's not to get in fights with Democrats," she said. "I want the Democrats to win. And I want a united Democratic Party that will stand against the Republicans," she said. Obama, who has raised more campaign money than Clinton from at least 258,000 individual donors, has waged close combat with her in recent weeks, pitting his demand for "fundamental change" against her insistence that Americans want her "strength and experience." DECEIVING DATA The Obama and Edwards camps are dismissing the polling numbers, pointing out that opinion surveys over the years have offered a skewed picture. A poll in August 2003, for example, showed the ultimate 2004 Democratic nominee John Kerry in fifth place behind other challengers. Obama is doing well in the early voting states of Iowa, New Hampshire and South Carolina, and Edwards is holding his own as well, especially in Iowa. Many believe the candidate who does well in those states will gain momentum for the contests ahead. "Polls will go up and down, but their irrelevance will not," said Obama spokeswoman Jen Psaki. "What we are focused on is introducing Barack Obama and his commitment to changing this country ... and what we are seeing is that the more people get to know Barack Obama, the more they like him." The Edwards camp attributed Clinton's boost in the polls largely to her name recognition. A senior Edwards official said the race is extremely fluid because many Americans appear willing to change their minds. "The history of America elections is littered with candidates who bragged about their high national poll numbers and their 'inevitability,' only to lose months later when voters in Iowa or New Hampshire realized they weren't the strongest candidate," said Edwards spokeswoman Colleen Murray. "The truth is, poll numbers aren't going to decide this election, voters will," she said. But the Clinton camp says the poll lead is significant and means her supporters consider her capable of defeating the Republicans in November 2008, or as Clinton herself said in the debate, "If you want a winner who knows how to take them on -- I'm your girl." Steve Elmendorf, a Democratic strategist who is a Clinton supporter, said the national polls matter because reporters, donors and activists take them into account. "Whether they're accurate or inaccurate, people look at them and they do shape some of the contours of the race," he said.