Is the race for president already over?
On one level, the answer is clearly no. Mitt Romney, Barack Obama and their surrogates are hammering each other in TV ads, speeches and interviews. And the party conventions and presidential debates are just around the corner.
But a growing number of political scientists and campaign consultants -- backed by the latest polling data -- think the daily campaign back-and-forth is having no significant effect on voters.
Most Americans have locked in their presidential decisions, polls released Thursday suggested, and the already small number of persuadable voters shrinks by the hour. Put another way: America could vote for president next week, and the outcome would probably be the same as it will be in November.
"That's accurate, barring some really big, big event or change in the political environment," said Alan Abramowitz, a political science professor at Emory University in Atlanta, who has studied presidential voting patterns.
Kenneth Warren, a political science professor at St. Louis University, agreed.
"Most people have decided who they're going to vote for early on," he said.
Recent polls show those who have decided are split almost evenly between Obama and Romney. In a CBS/New York Times poll, Romney led by 1 point. In a Fox News poll, he trailed Obama by 4 points. A National Public Radio poll found Obama leading by 2 points. A Gallup tracking poll over the same time period showed the race dead even.
The average of polls puts the Obama advantage at 1.2 percent, according to Real Clear Politics, a political aggregation website. The incumbent has led Romney in that average by a one- to two-point margin since last October.
Political scientists and consultants said there were several reasons for early presidential decision-making. In an Internet-cable-TV age, voters are pounded with political messages daily, helping them make up their minds far in advance of the election.
An incumbent in the race makes at least one of the candidates a known quantity. And American voters are deeply divided, further cementing their choices.
But the relative stability of the polls doesn't mean Obama will win. His margin is well within the polls' margins of error, strongly suggesting the White House is up for grabs. And Obama's consistent polling below 50 percent, experts said, is a danger sign for the Democrat.
History has shown, however, that July leads can slip. In 2004, Democrat John Kerry led incumbent George W. Bush by 1.9 points in the July 16 polling average. In November, Bush won by a 2.4 percent margin, a comeback that began in September of that year.
But this year's polling suggests daily attack ads -- whether on Romney's role with Bain Capital or Obama's problems with the sluggish economy -- aren't persuading many voters to switch sides.
"There is little in the way of persuasive evidence that the race is moving much in one direction or another," columnist Nate Silver wrote Thursday in The New York Times.
The polling also confirms studies of the last presidential election, where voter movement was limited. In 2008, 92 percent of voters locked in their presidential choices by June. The 8 percent who changed their minds, however, were roughly split between Obama and John McCain -- yielding virtually no effect on the outcome.
There are some circumstances, of course, that could change the state of the race.
A major foreign policy crisis, for example, could change voters' minds. In 1980, anger over the Iranian hostage situation damaged President Jimmy Carter in the final days of his race against Ronald Reagan.
Also, Abramowitz said, any dramatic change in economic conditions, such as higher food or gasoline prices -- "something that people could feel in their daily lives" -- could move the needle.
But he considers that unlikely. Even the 2008 economic meltdown, he noted, didn't move many voters.
The candidates could also make a serious campaign mistake -- a flubbed debate, a weak vice presidential choice or a messy convention could flip some voters.
"It depends on whether someone makes a huge blunder," Warren said. "And by the way, the people don't notice it. The media brings it out, and it can hurt."
Democratic consultant Richard Martin said a candidate also could make a tactical error. "McCain made a mistake" by picking Sarah Palin four years ago, Martin said, costing the Republican votes.
But again, such a serious misstep isn't considered likely. Romney is expected to pick a noncontroversial running mate, and though both he and Obama have said things in speeches they'd probably like to rephrase, neither candidate's lips have fatally slipped so far, most political observers agreed.
They said that meant the election would probably be decided by turnout and voter enthusiasm, and not a big swing by persuadable voters.
That's particularly true in crucial states such as Ohio, Florida and Iowa, where residents are now being inundated with political ads.
Because of the Electoral College, the national polling numbers may be less significant than the margins in battleground states, some observers said.
"Whatever is going on in the popular vote, it looks like this is going be decided by the electoral votes of nine to 11 states," said Dennis Goldford, political science professor at Drake University in Des Moines.
Johnson County Republican chairman Ronnie Metsker agreed.
"State by state is how they're going to look at it," he said.
But polls show state races are close as well. A Rasmussen poll released Thursday found Obama leading Romney 47 percent to 45 percent in Ohio, a key swing state.
"All signs are, this race is going to be won or lost by 1 or 2 percentage points," Warren said.