WASHINGTON - President Obama canceled a scheduled trip to Colorado Springs on Tuesday in order to monitor hurricane Sandy, but his campaign has added another visit to Boulder later in the week.

In an extraordinarily tight race, Hurricane Sandy has forced Obama and Republican Mitt Romney to toss out carefully mapped-out itineraries as the candidates work to maximize voter turnout while avoiding any suggestion they were putting politics ahead of public safety. Romney canceled plans to campaign in Virginia on Sunday, opting instead to join running mate Paul Ryan in Ohio.

"The storm will throw havoc into the race," Sen. Mark Warner, D-Va., said on "Fox News Sunday," noting that a Monday rally with Obama and former President Bill Clinton has already been canceled.

David Axelrod, a top adviser to Obama's campaign, said it was impossible to predict how the storm would affect the election but acknowledged it could drive down turnout to Obama's detriment.

"Obviously, we want unfettered access to the polls, because we think the more people that come out, the better we're going to do," Axelrod said on CNN's "State of the Union." "And so, to the extent that it makes it harder, that's a source of concern."

The Obama campaign has tentative plans for a rally in Boulder on Thursday. Details, including the time and location have not yet been released, reported the Daily Camera.

The visit would be Obama's third to Boulder this year.