Most registered Republicans and Democrats have long since made up their minds who they're going to vote for, so the presidential campaigns are poised to spend tens of millions of dollars trying to win over those who say they don't belong to either party.
"Most folks in the parties have made their decision already," says Lanae Erickson Hatalsky of the centrist Democratic think tank Third Way. "And so those independents, a bigger number of them, are now going to be the real key to victory in 2012."
David Winston, a Republican strategist, said such independents made up 22 percent of voters in 2002.
"In 2010, they had grown to make up about 29 percent of the electorate," he said. "So clearly as the exit polls have shown, they've grown quite a bit."
And a Gallup poll recently reported that independents account for 35 percent or more of voters in most recent elections.
Some political analysts, however, say many voters call themselves independents but really are not -- that the true number is less than 10 percent. If so, they're just as important:
"Even half of that means 3, 4, 5 percent, and in most of these battleground states the final results will be within 52 to 48 percent, so they could be and probably will be the critical voters," says Larry Sabato, a political analyst at the University of Virginia.
And one Republican analyst says independents have been key in recent swings of power in Washington.
"In 1994, when Republicans won the Congress, we won independents by 14 (percentage points)," Winston said. "In 2006, when we lost the Congress, we lost independent by 18. And we came back in this last election in 2010, we won independents by 19 points"
So what moves independent voters? President Obama has tried to convince them a policy of taxing the rich is best course, one "that asks the wealthiest Americans to help pay down our deficit, to do their fair share," he told one audience last month.
Third Way, the democratic think tank, however, polled voters in 12 battleground states and found independents don't buy the tax fairness argument.
"They don't see themselves as victims in the system, so about 60 percent of them say our system is basically fair," Hatalsky said. "For these folks in the middle, the independents, income inequality was not a good message for them. It didn't work."
"Look, the independent voter, particularly this year is -- a big chunk of them are college educated independents who don't buy the class warfare argument," said former Bush administration strategist Karl Rove, a Fox News contributor.
That might explain why several recent polls show Obama down several points among independents, even though he won them by 8 percentage points in 2008.
When it comes to the economy, independents in the Third Way poll didn't talk about fairness. They talked about opportunity and jobs -- on which the president says he's making progress.
"Moving forward, not moving backwards," he said to applause. "And we've been able to do that. We've been moving forwards."
The 23 million unemployed or underemployed may have a different view, including independents such as David Rivera, a 36-year Florida resident.
"Currently my wife is unemployed and it's hard, it's been hard to get another job. So, we are basically just a one income household," he said.
And that issue could determine the outcome of the election.
"The better-informed independents are practical. They want real problems solved with practical solutions," Sabato said.
"What I've found independents are looking for is, 'Tell me how you are going to get this economy moving forward -- don't tell me why somebody else is wrong,'" Winston said. "Explain to me how you're going to solve the economy and get things moving."
Jim Angle currently serves as chief national correspondent for Fox News Channel (FNC). He joined FNC in 1996 as a senior White House correspondent.