A day ahead of Tuesday's election, the Obama and Romney campaigns are dashing around eight pivotal states. The latest polls give President Obama a slight edge — a narrow lead in several key swing states that suggests he'll have an easier time than his rival mustering the 270 electoral votes needed to win in the Electoral College. Mitt Romney, however, has a clear if narrower path to the presidency. And several factors could decisively shift the electoral math. Here, four wild cards that could determine who spends the next four years in the Oval Office:

1. Hurricane Sandy
The superstorm that walloped New Jersey, New York, and several other states disrupted the presidential campaign, too. It's "distasteful to cast such a human tragedy in terms of electoral politics," says John Cassidy at The New Yorker, "but there's no getting away from the fact that [the] president's adroit response to the storm has had a significant effect on public opinion." Obama lagged behind Romney in national polls for most of October, yet after the storm winds settled he was suddenly back in the lead. "While there are a number of possible explanations for this turnaround, the most convincing is the simplest: His handling of Sandy has raised his standing, and his poll ratings." It's unclear how significant Obama's post-Sandy bounce was, but it might prove big enough to seal his victory.

2. Gary Johnson
The real "X factor" in this race, says Chris Miles at PolicyMic, is Gary Johnson. The former New Mexico governor — and former Republican — is making a nearly invisible third-party bid as the candidate of the Libertarian Party. He barely registered as a blip in the last comprehensive national poll that bothered including him, earning just two percent support. Still, chances are good he'll be the spoiler on Tuesday. "In Ohio — the swing state of all swing states — Johnson will likely tear a full percentage point away from Romney in the polls. With the presidential race as tight as it is, even that single point in Ohio could turn the election."

3. An Iowa surprise?
Iowa is a swing state with six potentially crucial electoral votes. It's considered likely to go for Obama, says Steve Deace at USA Today, but "a down ballot retention election involving one of the judges in the Iowa Supreme Court's controversial marriage ruling in 2009 may boost Romney's fortunes." Romney, a two-time presidential candidate, lost twice in a row in the Iowa Caucuses, a good indication that "the state's social conservative multitude isn't sold on him." Those same people, however, are itching to hold Justice David Wiggins "accountable for his role in the court's unpopular opinion decreeing marriage for homosexuals." Iowans "made history by voting to fire three of Wiggins' peers" in a 2010 election. If the state's social conservatives show up en masse to give Wiggins the boot, too, they'll surely pull the lever for Romney while they're at it, and "propel him to victory."

4. Virgil Goode
Virginia is likely a critical paving stone on Romney's path to victory. Polls suggest he holds a narrow lead over Obama in the state, but a potential hitch exists. Virgil Goode, a former Republican congressman, has secured a place on the ballot as the presidential nominee for the conservative Constitution Party. His presence in the race risks "complicating Mitt Romney’s chances of winning the key swing state," says Jonathan Weisman at The New York Times. The state's Republican Party has been trying to get Goode's name stricken from the ballot, saying his party used fraudulent signatures to qualify. "They're afraid true conservatives will vote for me," Goode says. Judging from the polls, Goode "may not win many votes," says the Times' Weisman, "but, in a close election, they may have outsize significance."

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