But the key for both campaigns is the Midwest, specifically Ohio. It offers 18 electoral votes and figures prominently in each strategy. That urgency was evident by the multiple visits to the state by each candidate in the final days.
Obama has enough of an edge in the electoral race that he could win the White House without carrying Ohio. But it's hard to see how Romney does so.
That assessment, and Obama's slight but stubbornly persistent edge in the state, could explain why Romney made a late-game play for Democratic-leaning Pennsylvania's 20 electoral votes. He began advertising heavily in the state last week and put a stop in Philadelphia on his Sunday schedule even though the state has voted for a Democratic presidential nominee in every election since 1988.
Democrats projected confidence about holding Pennsylvania, although Obama responded with his own ads in the state and was sending former President Bill Clinton to campaign for him there on Monday.
Not that Romney is writing off Ohio. No Republican has won the White House without winning the state, and, without it, Romney would need a near sweep of the other battleground states.
"Ohio, you're probably going to decide the next president of the United States," Romney said Friday at a plant near Columbus.
Refusing to cede ground in Ohio, Obama's campaign is flooding the state with four visits in as many days to every major media market by the president, first lady Michelle Obama, Vice President Joe Biden and Clinton. Obama planned to finish campaigning in Ohio on Monday at a Columbus rally with rocker Bruce Springsteen.
Obama's team was projecting confidence in Ohio, arguing that the renewed debate in the final weeks over the auto industry financial bailout — which Obama signed and Romney has criticized — has boosted the president at the right time while undercutting Romney. Republicans in the state don't dispute that characterization, and Obama has kept the heat on Romney over a TV ad he's running that misleadingly suggests that the auto bailout helped U.S. auto giants send jobs to China.
"This isn't a game. These are people's jobs. These are people's lives," Obama told a raucous crowd in Friday in a Columbus suburb. "You don't scare hard-working Americans just to scare up some votes."
Wisconsin, the home state of GOP vice presidential nominee Paul Ryan, also figures prominently in the calculations for both sides, but, again, is more critical for Romney, who is looking to stop Obama in the Rust Belt.
Here's why: Obama surest path to a second term cuts through both Ohio and Wisconsin, and victories in those states would give him 271 electoral votes as long as he wins all of the states that are solidly Democratic or tilting his way.
—Iowa, where public and internal campaign polls show Obama with an edge even though Romney has campaigned in the state a half-dozen times in the past two weeks and has spent the final hours of the campaign working to narrow Obama's edge in early voting. Both candidates were in Iowa on Saturday, and Romney was back Sunday playing hard for late-deciders his team is confident will break their way and make the difference.
Obama planned to return to the state Monday. Republicans characterized that visit as a sign of instability while Obama's team said he wanted to end his campaign in the state whose 2008 caucuses put him on the road to the presidency.
—Nevada, where Republicans and Democrats say the president has gained ground over the past few weeks, despite high unemployment and foreclosures. Obama seems to be benefiting from the state's large Hispanic voting bloc and political machinery of Senate Majority Leader Harry Reid.
Romney all but acknowledged the president had an edge in the states. He scrapped plans to visit the state in the final two days. Instead, he sent Ryan.
Associated Press writers Charles Babington in Florida, Brian Bakst in Virginia, Julie Pace in New Hampshire, Steve Peoples in Iowa and Ken Thomas in Washington contributed to this report.