They could turn a too-close-to-call race into a landslide for President Barack Obama -- but by definition they probably won't.

Call them the unlikely voters.

A nationwide USA Today/Suffolk University Poll of people who are eligible to vote but aren't likely to do so finds that these stay-at-home Americans back Obama's re-election over Republican Mitt Romney by more than 2-to-1. Two-thirds of them say they are registered to vote. Eight in 10 say the government plays an important role in their lives.

Even so, they cite a range of reasons for declaring they won't vote or saying the odds are no better than 50-50 that they will: They're too busy. They aren't excited about either candidate. Their vote doesn't really matter. And nothing ever gets done, anyway.

"I don't think Obama helped us as much as he promised," says John Harrington, 52, a heavy-equipment operator from Farmington, Minn. Since 2008, when Harrington voted for Obama, the financial downturn has forced him to sell his home in Arizona, move to Minnesota to be near a daughter and put him on the road to Nebraska, North Dakota and Iowa to find work.

His wife "loves" Obama and is sure to vote in November, but he's not certain whether he'll get there this time.

This year, perhaps 90million eligible Americans won't vote, said Curtis Gans, director of the nonpartisan Center for the Study of the American Electorate.

"The long-term trend tends to be awful," Gans says. "There's a lot of lack of trust in our leaders, a lack of positive feelings about political institutions, a lack of quality education for large segments of the public, a lack of civic education, the fragmenting effects of waves of communications technology, the cynicism of the coverage of politics -- I could go on with a long litany."

Jamie Palmer, 35, a mother of three from St. Joseph, Mo., has never voted. "If a candidate I liked ran for the presidency, that had the right things to say, I'd go vote," she says. "But they say the same things; they make promises; they don't keep them. It's ridiculous. If I vote, nothing is going to come of it. It's just going to be like it is right now."

A big disconnect

Many of these unlikely voters are suspicious of and disconnected from politics. In the survey, six in 10 say they don't pay attention to politics because "nothing ever gets done"; 54 percent call politics "corrupt." Only 39 percent could correctly name the vice president, Joe Biden. (By contrast, a Pew Research Center poll in 2010 found 59 percent of American adults could name the vice president.)

On the other hand, they do see a difference between the two major parties: 53percent disagree with the statement that "there's not a dime's worth of difference between Democrats and Republicans." Obama scores a huge advantage among all the unlikely voters. By 43percent to 18percent, they support the Democratic incumbent over his Republican challenger.

"There's this pool of people that Barack Obama doesn't even need to persuade," says David Paleologos, director of the Suffolk University Political Research Center, which took the survey. "All he needs to do is find them and identify them and get them to the polls. It's like a treasure chest. But the bad news is that the treasure chest is locked.

"You've got this overriding sense of bitterness and people who have been beaten down by the economy and the negativity and the lack of trust, and that's the key that Obama can't find. And he's running out of time."

Two-thirds of the unlikely voters say they voted four years ago, backing Obama by more than 2-to-1 over Republican John McCain. That helps explain why Obama's campaign is spending millions of dollars on the most elaborate field operation in U.S. political history, aimed at delivering both core supporters and reluctant ones to the polls.

Who's unlikely to vote?

Many of the nation's unlikely voters report hard times over the past four years. Only a third call their household finances good or excellent. Close to half say their annual household income is less than $60,000 a year. They tend to have lower levels of education than likely voters; nearly six in 10 have no more than a high school diploma.

The ranks of eligible nonvoters lean toward the Democratic candidate in most though not all election years. The Democratic tilt among them is much greater in this survey than it was in 2004 or 2008 in the Gallup Poll just before Election Day. Then, Democrats had the advantage in voter enthusiasm -- an asset they've lost this year.

The process of registering to vote doesn't seem to present a major obstacle. Two-thirds say registering is easy and can be done pretty quickly; 16percent say it takes too much time and is too complicated. The new wave of voter ID laws, which experts predict may reduce turnout a bit, doesn't seem to be an issue: 75percent support requiring citizens to show a photo ID.

The top reason given by unregistered voters for not having signed up is their busy lives. Among the top reasons given by registered voters for not bothering to go to the polls: not liking either candidate and not feeling that their vote matters.

About one in 10 say they could be drawn by different candidates, by being convinced someone could fix the nation's problems, and by feeling better informed. Asked to name someone whose presidential bid would prompt them to vote, Secretary of State Hillary Rodham Clinton was the most frequently cited, by 7percent. Texas Rep. Ron Paul, who sought the GOP nomination, was next, named by 3percent.

Annie Provencher, 60, a retired cashier from St. Pauls, N.C., voted for Bill Clinton and for Democrat John Kerry in 2004. She didn't vote in 2008, and she's not sure she will this time. She knows she doesn't like Obama but isn't sure about Romney.

If Hillary Clinton were running, she volunteers, "I'd be back there, the first one in line when the polls opened."