President Barack Obama and Republican challenger Mitt Romney engaged in frantic get-out-the-vote efforts and made final pleas to voters on Monday in a sprint through battleground states that will determine who wins their agonizingly close White House race.
Both candidates sought to generate strong turnout from supporters and to sway independent voters to their side in the last hours of a race that polls showed was deadlocked nationally. Mr. Obama had a slight lead in the eight or nine battleground states that will decide the race on Tuesday's Election Day.
The latest Reuters/Ipsos national poll of likely voters, a daily tracking poll, gave Mr. Obama a slight edge, with 48 per cent support compared to Mr. Romney's 46 per cent. The difference was within the 3.4 percentage point credibility interval, which allows for statistical variation in Internet-based polls.
Mr. Obama was up four percentage points in must-win Ohio, 50 per cent to 46 per cent, and held slimmer leads in Virginia and Colorado. Mr. Romney led in Florida by one percentage point, the poll found.
The president, with a final day itinerary that included stops in Wisconsin, Ohio and Iowa, urged voters to stick with him and trust that his economic policies are working. Traveling with him was rocker Bruce Springsteen.
"Ohio, I'm not ready to give up on the fight. I've got a whole lot of fight left in me and I hope you do too," Mr. Obama told supporters in Columbus, Ohio.
Mr. Romney's day included stops in Florida, Virginia, Ohio and New Hampshire. He pledged that he would handle the economy better than Mr. Obama and jabbed his opponent for blaming Republican predecessor George W. Bush for the weak economy.
"I won't waste any time complaining about my predecessor. And I won't spend my time trying to pass partisan legislation rather than working to help America get back to work," Mr. Romney said in Fairfax, Virginia.
The candidates are seeking to piece together the 270 Electoral College votes needed for victory in the state-by-state battle for the presidency. Despite the close national opinion polls, MR. Obama has an easier path to victory: If he won the three states he was visiting on Monday - Wisconsin, Ohio and Iowa - then he would likely carry the day.
Ohio could be decisive
All eyes were on the Midwestern state of Ohio, whose 18 electoral votes could be decisive. Mr. Romney, looking for any edge possible, planned last-second visits on Tuesday to both Ohio and Pennsylvania, aides said.
Visits to the areas around Cleveland and Pittsburgh would be aimed at driving turnout. And the Pittsburgh stop could be as much about Ohio as Pennsylvania, since many in eastern Ohio watch Pittsburgh television.
Mr. Romney's path to the White House becomes much harder should he lose Ohio. The state has been leaning toward Mr. Obama - its unemployment rate is lower than the 7.9 per cent national average and its heavy dependence on auto-related jobs meant the bailout to auto companies that Mr. Obama pursued in 2009 is popular.
Both campaigns expressed confidence that their candidate would win, and there were enough polls to bolster either view.
There were clear signs that Mr. Obama held an edge. A CNN/ORC poll, for instance, showed him up in Ohio by 50 per cent to 47 per cent.
The close margins in state and national polls suggested the possibility of a cliffhanger that could be decided by which side has the best turnout operation and gets its voters to the polls.
Whoever wins will have a host of challenges to confront. The top priority will be the looming "fiscal cliff" of spending cuts and tax increases that would begin with the new year.
The balance of power in Congress also will be at stake on Tuesday, with Mr. Obama's Democrats now expected to narrowly hold their Senate majority and Mr. Romney's Republicans favored to retain control of the House of Representatives.
In a race where the two candidates and their party allies raised a combined $2-billion, the most in U.S. history, both sides have pounded the heavily contested battleground states with an unprecedented barrage of ads.