Charlie Neibergall/AP Photo

A day before the nation's first primary in New Hampshire, Republican front-runner Mitt Romney is busy courting independent voters, a burgeoning group that has the power to sway the results in this year's presidential election.

Forty percent of voters identified themselves as politically independent in 2011, according to a new Gallup poll released today, the highest number recorded in the poll yet. The previous high for independents was 39 percent in 1995 and 2007. Democrats won both presidential races in the following years.

Independent voters are an increasingly important voting bloc. They have outnumbered both Democrats and Republicans continuously for the past two and a half years, by far the longest period in which they've done so in ABC News-Washington Post polls dating back to 1981.

Gallup's recent poll bears mixed news for the two parties. While the gap between those who identified as Democrats and those who said they were Republicans widened to 4 percent, more independents appeared to lean toward the Republican Party than to the Democratic Party and the split between the two was equal.

"Increased independent identification is not uncommon in the year before a presidential election year, but the sluggish economy, record levels of distrust in government and unfavorable views of both parties helped to create an environment that fostered political independence more than in any other pre-election year," Gallup stated.

Some experts, however, advise caution about the potential impact of independent voters in this election cycle, citing data showing that most in this voting bloc are still partisan and tend to lean more on one party or the other.

Additionally, many Americans who identify themselves as independent have little interest in the political process and might not actually show up in the polls to vote.

Swing voters, experts say, are really the ones who are influential and can be swayed either way in the general election. But they are a lot smaller commodity than independents generally.

Swing voters played an important role in 2008. Along with minority groups and the youth, they helped propel Barack Obama to the presidency.

"There is a tendency to exaggerate the proportion of independents in the electorate and their impact on the election," said Alan Abramowitz, professor of political science at Emory University in Atlanta. "When you narrow it down, look at actual voters, the turnout rate among independents is lower. When you look at actual voters and look at those who are truly uncommitted, you find that you're down to less than 10 percent of the actual voters."

Obama's win in 2008, Abramowitz says, was in large part because of President George W. Bush's unpopularity and the dismal economy, which pushed higher-than-normal independent voters to take to the polls.

But others refute the idea that the influence of  independent voters is a myth, and argue that even though they might lean toward one party, that preference can change over time and is a point that candidates should keep in mind when campaigning.

"Independent voters are no myth, they matter, and (when you include among them independent partisans) they absolutely sway elections," wrote Todd Eberly, an assistance professor at St. Mary's College of Maryland. "Indeed, the present and highly competitive political era in which we are living is a direct result of a decrease in partisan attachment among a growing number of voters."

Where these independent voters are concentrated will also make a difference in the general election.

"Obviously, their influence is going to depend on where they are. It doesn't matter if you have a bunch of independent voters tussling in Texas because the state is so overwhelmingly Republican," said Victoria M. DeFrancesco Soto, a senior fellow at the Bernard Center for Women, Politics & Public Policy in Potomac, Md.

Still, the key for candidates on both sides of the political aisle this year will be to energize the base and get them to vote, as is evident in the trends on both sides thus far.

"The key thing Obama campaign needs to do - not to say they should neglect swing voters - but it's more important for them to make sure they get their own base unified," Abramowitz said. "He's probably not going to do as well with swing voters this time because he's not going to have George Bush in the White House."

Many in this voting bloc also feel that Obama has failed to live up to his promises of change and hope.

For Republicans, reaching out to independents is just as challenging of a task, if not a bigger one. They have the added pressure of not only courting a Republican base divided on the candidates, but wooing voters in moderate states such as New Hampshire and Florida where independents make up a large chunk of the voting bloc in the primaries. And if Iowa is any indication, that group is likely to come out strong Tuesday night. Independents turned out in bigger-than-usual numbers in the nation's first caucus and helped push Rep. Ron Paul to a third place finish in Iowa.

It could be an important group for Republicans in November as they vie to beat the incumbent president. But attracting swing voters could be a tough task in an environment where the Republican base is growing increasingly conservative.

Romney has been struggling to sell his conservative credentials to a Republican base that's wary of his record on health care and other moderate policy stances as governor. The independent vote could help him make up for the loss that might result from that skepticism, but it will be a difficult task, experts say.

Whoever the GOP candidate is will have to show that he's "not just about the base but they're for the large audience," Soto said. "It's about America. It's about getting our country on track, not about catering to the base, which will be difficult for Romney to do because he has spent months and months on the base and he would have to pivot."

Romney has been targeting independent voters in New Hampshire, a socially liberal state where there are more undeclared voters than either Democrats or Republicans. Because they can vote in the GOP primary - up to 44 percent of voters in Tuesday's primary are expected to be undeclared - this bloc is key to ensuring that the former governor of neighboring Massachusetts emerges victorious.

The same is true of Florida, where polls show independent voters could make a difference. Unregistered voters account for about a quarter of the electorate in the Sunshine state.