Powered by polished debate showings, gaping opinion poll leads, and a pitch-perfect political machine, Hillary Clinton seems to be barnstorming towards the 2008 Democratic presidential nomination.

"If she continues to campaign without making a major mistake, it’s hard to see how anybody beats her," said Cary Covington, professor of political science at the University of Iowa.

"It is a lot like a chess match, and she has the superior board position."

Yet, US history is littered with the figurative graves of past front-runners. At the equivalent stage of the 2004 race, Senator Joseph Lieberman led national Democratic polls and Howard Dean was top in key states.

Both campaigns quickly fizzled.

So, there is still time for Clinton to make a killer error, or for one of her rivals to catch fire.

In Democratic debates, Clinton "is coming across as much more seasoned, much more experienced," said Costas Panagopoulos of Fordham University’s campaigns management program.

In a Quinnipiac University poll last week, Clinton led Obama by 36 percent to 21 percent among Democratic voters.

An average of national polls by website Real Clear Politics put Clinton on 39 percent, Obama on 21 and Edwards on 12 percent.

She also tops potential match-ups against Republicans — edging out top Republican Rudolph Giuliani by 46 percent to 43 percent in the Quinnipiac poll.

Fifty-nine percent of Democratic primary voters surveyed by CBS last week felt Clinton had the "right experience" to be president, compared to just 29 percent for Obama.

Clinton is also posing as the best candidate to battle Republicans.

"For 15 years, I have stood up against the right-wing machine, and I’ve come out stronger," she said in a debate in Chicago.

"If you want a winner who knows how to take them on, I’m your girl."

Clinton’s political machine meanwhile functions like a shadow White House, locking horns with the Bush administration on top issues, with master campaigner, former president Bill Clinton just off stage.

"She has always been good, she has the best advisor in the business, it is a very smart team and they know what they are doing," said Dan Shea, professor of politics at Allegheny College, Pennsylvania.

But Clinton’s challengers are not giving up.

Obama, hoping for a tsunami of change in 2008, branded Clinton "Bush-Cheney lite" on foreign policy and a voice of the past.

He touts his judgment and opposition to the Iraq war, which Senator Clinton voted in 2002 to authorize, plays to huge campaign trail crowds and outraises her in the multi-million dollar fundraising stakes.

"The amount of money that Barack Obama has raised is really very impressive, it means he is going to continue to have a seat at the table," said John Geer, professor at Vanderbilt University, Tennessee.

Clinton’s rivals say national polls mean nothing, and point to surveys in key states like Iowa which forsee a close three-way race.

Polls also show Clinton’s personality is still a question.

"The ‘Hillary hostility’ factor is constant and feeds doubts about whether she can win in November 2008," said Maurice Carroll, director of Quinnipiac University polling institute.

In the Quinnipiac poll, 43 percent of all voters had an "unfavorable" view of Clinton. Only 22 percent had an unfavorable impression of Obama.

Obama is taking notice.

"I believe I can bring the country together more effectively than she can," he told the Washington Post this week.

Edwards also took a shot.

"People in this country either love Hillary Clinton or they don’t," he told MSNBC.

President George W. Bush’s political guru Karl Rove meanwhile told the Wall Street Journal that Clinton was a "tough, tenacious, fatally flawed candidate."

Obama may also be yet to reach his peak.

"If he hits his stride, he could conceivably pull past her," said Geer. "I would not want to bet my house on her being the nominee, quite yet."

But Clinton’s rivals need to give history a nudge.

"Sitting around and waiting for her to screw up is not the wisest strategy," said Panagopoulos.

Source: Yahoo