Image caption Ron Paul's support was buoyed by independent voters

Independent voters are at an all-time high in the US. But who are they?

This week, the Gallup organisation reported that more Americans identify as "independent" than ever before, and now well outnumber their Republican and Democratic counterparts.

Forty percent of Americans defined themselves as independent voters, compared to 27% who said they were Republicans and 31% who said they were Democrats, according to Gallup.

In the New Hampshire primary almost half the voters identified as independent, buoying support for the eventual second-placed candidate, Ron Paul.

The rise of independent voters speaks to the electorate's increasing frustration with the current political climate. But it is also a particularly American phenomenon based on centuries of political and social narrative.

Proud decision

"Independent" is more than a political label indicating [someone who is] not identified as a Democrat or Republican, says Nancy Rosenblum, professor of government at Harvard, in an email to the BBC. "It broadcasts wholesale anti-partisanship."

In that sense, calling oneself "Independent" is as much about declaring an identity as rejecting one.

The need to publicly declare one's politics is a very American trait. Planting one's flag as a Democrat or Republican - and then displaying bumper stickers advertising that fact - might seem unthinkable in Europe.

Fourth of July is called 'Independence day.' Being independent is like a patriotic label Larry Powell, Political science professor

But the need to declare political preference extends beyond those who have selected a party.

"In other countries, citizens would never think of themselves as independent," says Paul Beck, professor of political science at Ohio State University.

"They might think of themselves as not-partisan," he says, but that wouldn't constitute a political identity.

"Declining party identification - 'no preference' on a survey of political attitudes - is a general phenomenon in advanced democracies, but the proud self-designation 'Independent' does not have a counterpart in other places," says Ms Rosenblum, author of On the Side of the Angels: An Appreciation of Parties and Partisanship.

Indeed, international respondents who label themselves without a party are more likely in fact to be apolitical - to refrain from voting and not to follow politics, says Mr Beck.

In the US, those types of citizens make up just one faction of independent voters.

A 'patriotic label'

Aside from the apolitical, independent voters are "closet partisans" and "conflicted voters", says Simon Jackman, professor of political science at Stanford University.

"For the last five years the biggest group of people of people we find in surveys are independents," says Mr Jackman, a principal at the American National Election Studies, which has been compiling voting data since 1948.

"A lot of people in response to some of the polarisation can't bring themselves to say they're with one group or another," he says, adding that they do still want to participate in the political process.

"That is the single largest category we see."

It has long been known by political scientists that self-labelled independents are often partisan towards one party, and tend to vote for that party consistently.

This was first brought to light in 1992 in a book called The Myth of the Independent Voter. The theory was reiterated in 2009 by political scientist and blogger John Sides.

An independent candidate? Image caption Independent candidate Ross Perot split the vote in 1992 Ross Perot ran a self-financed independent campaign in 1992, and his effect on the election is often credited with assisting Bill Clinton's victory. With independents at a new high, could another independent candidate play a factor in 2012? Analysts are sceptical. "The parties are a little more sophisticated. Anything they can do to try and prevent it, they would," says Jeffrey Jones, managing editor of Gallup.com. At the same time, he notes, the parties would not be able to stop an independent candidate with overwhelming support. But Mr Jones says that the rise of independent voters doesn't necessarily correspond with a demand for an independent candidate. "Usually we see the highest percentage of independent voters in the year before an election, but as the campaign wears on, the lowest rate we would see in a four-year cycle is in election year," he says. Come November, he believes that the rate will go down as self-proclaimed "independents" begin picking sides.

His analysis of voter data during the 2008 presidential election showed that "[t]here is very little difference between independent-leaners and weak partisans."

Some 75% of "independent leaners" are in fact "loyal partisans", he said.

And yet, these voters can't bring themselves to declare a party.

That is in keeping with several American values and beliefs: independents, it is believed, hews to no party because they think for themselves. They mull over each issue to find the candidate that best fits their individual needs and opinions, instead of blindly voting down party lines.

"Americans are very individualistic, and this country has become more and more individualistic every decade," says Steffen Schmitt, professor of political science at the University of Iowa.

"They don't want to be part of anything organised." He notes that his students, while politically engaged, increasingly decline to affiliate with a party.

The US, says Nancy Rosenblum, has a "deeply rooted civil idea of self-reliance as a virtue in economic and social life".

"Historically, as voting became the ritual expression of citizenship, partisanship began to be cast as degraded citizenship," she says, and voting along partisan lines was seen as a sign of both gullibility or cronyism.

"It's part of our heritage," says Larry Powell, professor of political communications at the University of Alabama. "Fourth of July is called 'Independence day.' Being independent is like a patriotic label."

Fractured system

But political scientists warn against romanticising the independent voter.

"We've glorified independents into thinking they are people who are weighing the properties and policies," says Mr Beck. "The truth is while there are some independents like that, most independents know much less about politics than partisans."

Others worry that the fracturing of the partisan system makes it difficult for independent voters to fully participate and have an impact on American democracy. Democracy is built on working together to achieve objectives - and independents make that work more difficult, some say.

"They are not sending a co-ordinated message," says Ms Rosenblum. "[Independents] do not assume responsibility for the institutions that organise public discussion, elections and government and are not responsible to other like-minded citizens."

Because independent voters represent a wide variety of viewpoints, and because there are rarely viable third-party or independent candidates, the principled stand taken by independents is often moot come election time.

"It's a two-party system," says Mr Jackman.

"When push comes to shove, when it's time to vote, they'll revert to type in the ballot box."