Aides to U.S. President Barack Obama and Republican rival Mitt Romney predicted election victory as the candidates headed for the campaign's last day Monday.
"It is going to be a big win for Governor Romney," Romney campaign Political Director Rich Beeson told "Fox News Sunday."
Romney himself told a crowd in Cleveland Sunday it was "possible" Obama would win Tuesday "but not likely."
Beeson told "Fox News Sunday" the Romney campaign had "expanded" the electoral map beyond traditional Republican strongholds to states such as Pennsylvania, where polls have indicated Obama's edge is narrowing.
"It looks like the map is expanding drastically in our favor and it's nothing we are doing -- it's Governor Romney's message," he said.
He suggested Romney could capture more than 300 electoral votes on Election Night. A candidate needs 270 electoral votes to win the presidential election.
Obama campaign Senior Strategist David Axlerod told the Fox program Romney's focus on states such as Pennsylvania was a sign of desperation.
"They have tried to expand the map because they know that in the states like Ohio, where they have to win, no Republican has ever been elected without carrying the state of Ohio," he said. "They are behind and they're not catching up at this point.
"And they are also going to be in Florida and Virginia, two states that you would assume by now they would have secured -- at least they assume by now they would secure," he said.
"They understand that the traditional, or the battleground, states on which we have been focusing are not working out for them," Axlerod said. "We're ahead in all of them, and now [Romney campaigners] are looking for somewhere, desperately looking for somewhere, to try and dislodge some electoral votes to win this election. And I can tell you that's not going to happen."
The latest United Press International poll indicates Obama and Romney are tied at 48 percent among likely voters.
A separate UPI poll indicates the race has narrowed to results in five states -- Colorado, Iowa, New Hampshire, Ohio and Virginia.
In Colorado and New Hampshire, Obama and Romney are tied at 49 percent each, the UPI-CVoter poll released Friday indicated. In Iowa, Ohio and Virginia, the gap between the two candidates is 1 percentage point, well within the margin of error for each state.
Colorado, Iowa, New Hampshire, Ohio and Virginia represent 50 of the 538 electoral votes. Electoral votes are based on the total voting membership of Congress, plus three electors from the District of Columbia.
Both UPI polls have error margins of 4.5 percentage points.
A separate poll released Sunday by the Pew Research Center/Princeton Data Source/Abt SRBI found Obama with a 3-point lead nationwide among likely voters, 48 percent to 45 percent. A week ago, the same poll had the two candidates tied. The latest Pew poll has an error margin of 2.2 percentage points.
A CNN/ORC International survey Sunday showed the race deadlocked at 49 percent among likely voters. That survey's sampling error is 3.5 percentage points.
Romney was to end his 524-day campaign Monday with a last sprint through Florida, Virginia, Ohio and New Hampshire.
On Sunday he told a crowd in Des Moines, Iowa: "We're only two days away from a very different path, from a fresh start. Two days away from a new beginning."
He also campaigned in Ohio, Pennsylvania and Virginia Sunday.
Obama was to close out his campaign Monday in Wisconsin, Ohio and Iowa. His Iowa remarks in Des Moines were to be with first lady Michelle Obama.
The president was introduced in Concord, N.H., Sunday by former President Bill Clinton, who said, "Folks, the hour is late and the time is short."
Obama said, "I'm here today because I'm not ready to give up on the fight."
Obama also campaigned Sunday in Florida, Ohio and Colorado.
