With more than two months to the first primary votes, the potential for mistakes and revelations about candidates means that the 2008 presidential race is far from a fait accompli.

Many people haven't been paying attention to the primary race on either the Democratic or Republican side. Recent polling shows that more than half of all voters in the early primary states have not yet formed their final opinions.

That means the toughest days lie ahead for national frontrunners Rudy Giuliani and Hillary Clinton, who are certain to see their races tighten up despite commanding leads in public preference polls.

The same goes for Mitt Romney, who is running ahead in New Hampshire, but seeing his race tighten. His monster lead of the summer is gone and all the other candidates are doing their best to take him down another notch.

According to the Marist Poll released Sunday of Republicans and Republican-leaning independents in New Hampshire, Romney leads with 25 percent compared to Giuliani's 21 percent. Arizona Sen. John McCain is in third place with 18 percent followed by Fred Thompson with 10 percent.

Romney is trying to hold onto his lead by staking his claim as the most conservative candidate in the GOP race, and his campaign spokesman said the candidate represents "the principles most important to Republican voters."

But Romney's opponents are having none of that, and Thompson's spokesman decried Romney as a wolf in sheep's clothing.

"In 1994, Mitt Romney accomplished what people had long thought was impossible — he ran for Senate to the left of Ted Kennedy. I didn't know there was any room there. For him to now claim to represent the Republican wing of the Republican Party is yet another Mitt Romney flip flop," said Thompson's communications director Todd Harris.

McCain too questioned Romney's claim to the Republican mantle.

"When he ran for office in Massachusetts being a Republican wasn't much of a priority for him," McCain said. "In fact, when he ran against Ted Kennedy, he said he didn't want to return to the days of Reagan-Bush. I always thought Ronald Reagan was a real Republican."

Speaking on CBS' "Face the Nation," McCain also challenged Giuliani's Republican credentials after Giuliani last week defended his opposition to giving President Clinton line-item veto authority.

"The line-item veto was declared unconstitutional because of the way it was written. We all know that if you write it the right way that you'll give the president of the United States the same power that 43 out of 50 governors have, and all of them say it's an essential tool," McCain said. "And so it is in direct contradiction, I think, to a fundamental Republican principle of being economic conservatives and eliminating waste and pork-barrel projects if you oppose the line-item veto."

Asked who the real Republican in the race is, Giuliani, who also won 44 percent of the Marist Poll survey about who would do best in the general election against a Democrat, said he'll let voters decide.

"This is what we're having a primary for. I think we should let the Republican Party decide," Giuliani said.

As for Democrats, the New York senator is leading in an American Research Group poll of 600 Democratic voters who say they will definitely vote in their caucus or primary. In the poll out Sunday, Clinton leads nationally over Barack Obama 34 to 31 percent with John Edwards at 15 percent. Still, 14 percent of those surveyed between Oct. 9-12 said they were undecided.

That's among the narrowest of polling lately on the Democratic side, where Clinton-slayers are trying desperately to demonstrate her weaknesses, particularly on foreign policy relating to Iran and Iraq.

Edwards called Clinton's recent vote for an amendment labeling the Iranian Revolutionary Guard Corps a terror group a sign that she's ingenuous.

"We read that some of Senator Clinton's advisers are saying that her vote on Iran was part of her moving from primary mode to general election mode. We don't need a candidate who has a primary mode and a general election mode — we need a candidate whose only mode is truth telling. That's what we need in our president too. There is too much at stake in this election for any voter to be forced to question the sincerity of the Democratic nominee," Edwards said.

Clinton and Giuliani's commanding leads in each of their party's contests, bolstered by high name recognition, is no sure sign that the stakes won't change. In 2003, three men led in most polls: Joe Lieberman, Wesley Clark and Howard Dean. Sen. John Kerry, the eventual Democratic nominee, was weak throughout most of 2003.

FOX News' Carl Cameron and Caroline Shively contributed to this report.