CLEVELAND -- GOP presidential nominee Mitt Romney reassured a crowd here that he believes Republicans will emerge victorious on Tuesday.

Mitt Romney attends a campaign rally in Cleveland, Ohio, November 4, 2012. (Jim Young/Reuters)

"If the president were to be reelected," Romney began to tell the audience of about 6,000 supporters gathered at the cavernous International Exposition Center halfway through his stump speech. He was interrupted by boos.

"It's possible, but not likely," he added.

At the event, Romney's second of the day, the GOP nominee was preceded by performances by Rodney Atkins and Sam Moore. He was on the ground for only a few hours before heading out to his next rally in Pennsylvania, a blue state that Republicans maintain remains within their reach.

A reminder of Ohio's centrality to both campaigns could be found at the Cleveland airport Sunday afternoon, where Romney's plane was parked just across the tarmac from Air Force Two. According to a White House pool report, Vice President Biden caught a glimpse of the Romney plane before boarding his own jet.

Some Republicans, including former Mississippi governor Haley Barbour, have suggested that Romney's momentum was blunted by Hurricane Sandy. Asked Sunday about such claims, Romney adviser Kevin Madden dismissed them.

"I don't look at what happened with the storm and how it affected so many people through a political lens," he told reporters aboard Romney's plane en route Cleveland, noting that he believes Romney will win on Tuesday. "Instead, we are focused on what we can do to make sure that the enthusiasm that we have seen in states, that it's -- part of helping our get out the vote efforts in all these key battlegrounds and then just focusing on the message."

"So, I wouldn't entertain the same notion that those folks did," he added.

Madden also dismissed criticism that the GOP ticket is paying attention to Pennsylvania too late in the game.

"We see it as the perfect time, given that you're 48 hours from people making a decision, given that they don't have early voting there," he said.