Statisticians have said for weeks that President Obama is the overwhelming favorite to win Tuesday's election, even though polls say he's in a dead heat with Mitt Romney nationally. The reason: Obama has narrow but significant leads in most of the swing states that will likely cast the deciding votes in the Electoral College. But now, some analysts are moving all-powerful Ohio, which has steadily leaned Obama, into the "toss up" column, saying the race there has tightened. Republicans have accused statisticians of pro-Obama bias, and Romney political director Rich Beeson says all signs indicate that Obama's electoral firewall "is burning." Predictably, Team Obama disagrees, insisting it's clearly holding. Are Republicans fooling themselves, or is Obama's swing-state firewall really breaking apart?

The firewall is crumbling: Obama's famous get-out-the-vote machine was a key building block in his "impregnable firewall," says Jim Geraghty at National Review. The idea was that Obama would build up such an advantage in early voting that Romney wouldn't be able to catch up on election day. Early voting figures, however, suggest that Obama's ground game isn't expanding his share of the vote in crucial states such as Ohio, and he's behind his 2008 pace in Virginia, too. Ouch.
"Tough news for Obama in early voting figures"

The wall was shaky, but not anymore: Obama had some terrible days in early October, says Nate Silver at The New York Times. It looked like his firewall wasn't "all that it was cracked up to be." Romney's momentum has since faded, though, and Obama has "rebounded slightly." He's on firmer footing nationally, and still has "the lead in the vast majority of polls in Iowa, Nevada, Ohio, and Wisconsin," the states on his "path of least resistance toward winning the Electoral College."
"Oct. 31: Obama's Electoral College 'firewall' holding in polls"

The question is, which polls are right? Going into the last five days of the campaign, the polls are all over the map, says Mark Blumenthal at The Huffington Post. There have been 11 recent polls in Ohio, for example, and they suggest Obama's lead there is anywhere from one to five percentage points. There are similar gaps in other swing states. If Obama's margins are overstated by just a couple of points, the firewall goes poof. That's unlikely, but "within the realm of possibility." So the question is, how accurate are the polls?
"Could presidential polls be wrong about Obama's battleground edge?

Read more political coverage at The Week's 2012 Election Center.