Mitt Romney could be the first Republican to win the White House without winning Ohio — if he can flip Pennsylvania.

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ith one day left before Election Day, both campaigns are "talking about how their man will prevail on Tuesday," says David Jackson at USA Today. The national polls are essentially tied, with President Obama enjoying the slimmest of leads. But the electoral college math is more encouraging for the president, as he seems to have far more paths to electoral victory than Mitt Romney. Still, Romney adviser Ed Gillespie argues that his team has successfully expanded the number of in-play states, notably Pennsylvania, where Romney held a large rally Sunday night. "When you look at where this map has gone, it reflects the change and the direction and the momentum toward Governor Romney," Gillespie said Sunday. Team Obama is equally confident, but of course, both men can't win. Here's how Romney can capture the necessary 270 electoral votes to be the next president of the United States.

Romney starts out with 206 safe or leaning electoral votes, including North Carolina (which Obama won in 2008), versus 249 for Obama, according to the AP. Up for grabs are the 83 electoral votes spread across Colorado, Florida, Ohio, New Hampshire, Virginia, and Wisconsin. According to a New York Times tally, which adds Iowa, Nevada, and North Carolina to the toss-up category, Romney has 76 distinct paths to electoral victory. Almost all of them start with Florida. His most likely route is Florida, Virginia,, North Carolina, Colorado, and Ohio. If Romney loses the Sunshine State, he can still win, but he has to sweep Virginia, Ohio, North Carolina, Colorado, Wisconsin, Iowa, Nevada, and New Hampshire. (Play with the electoral map yourself at CNN.)

For all the talk about Ohio — and yes, no Republican has ever won the White House without it — Romney can win even if he loses the Buckeye State and its 18 electoral votes. The quickest way would be to flip Pennsylvania (20 electoral votes), something the GOP hasn't done since 1988. But Romney could also do it by winning a number of closely contested states: Florida, Virginia, North Carolina, Colorado, New Hampshire, and Wisconsin or Iowa and Nevada. That's the electoral equivalent of drawing an inside straight. Which is why Romney has visited Ohio at least 44 times in the general election campaign.

As you watch the election returns, says Ruby Cramer at BuzzFeed, you'll be able to tell if Romney is winning as early as 7 pm (ET). That's when Virginia polls close, and if Romney loses, he's probably lost the election. That's also true of North Carolina and Ohio (7:30 ET), and Florida (8 ET). If Romney wins all those plus Pennsylvania (also 8 ET), he's won the presidency. If he wins all those but falls short in the Keystone State, he can cinch it by winning Wisconsin (9 ET). Otherwise, watch New Hampshire (8 ET), Colorado (9 ET), and Nevada and Iowa (10 ET) — with Ohio plus the other three core states, if Romney takes any of those, he wins.

Can he pull it off? It's technically possible, but Team Romney is "in deep trouble," Obama chief strategist David Axelrod said Sunday. "They understand the battleground states where they've been working is not working out for them." Team Romney, of course, disagrees. It's all about getting people to the polls, especially those who don't normally vote — and Romney's turnout will surprise people, says Romney political director Rich Beeson. "We've done a much, much better job of getting our low propensity voters out to vote. And we've got all of our high propensity voters ready to go vote on Election Day."

Sources: AP, BuzzFeed, CNN, Fox News, New York Times, Washington Post, USA Today

Read about Obama's paths to electoral victory here.