NORFOLK, Va. - Hurricane Sandy scrambled the plans of presidential candidates as the storm barreled toward battleground Virginia and the rest of the East Coast Sunday.

After conferring with Gov. Bob McDonnell about the additional strain the campaign could impose on emergency personnel already in motion to deal with a potentially historic storm, President Obama, Vice President Biden and Republican contender Mitt Romney all canceled planned visits to a state critical to the fortunes of both sides.

Romney late Friday scrapped a rally planned for Sunday at the 20,000-seat Farm Bureau Live amphitheater in Virginia Beach. A day later, Romney canceled the rest of his Virginia schedule and shifted his campaign temporarily to Ohio instead.

Biden also canceled a Virginia Beach event scheduled for Saturday. Obama scratched a Monday appearance in Prince William County as well as a trip to Colorado, aides said, so he could monitor emergency preparations for Sandy from the White House.

"I appreciate the candidates working with us so there's no interruption with our law enforcement to get ready for and prepare for this storm," McDonnell told reporters Sunday.

Sandy affected Virginia's hotly contested U.S. Senate race as well. Republican George Allen was supposed to make a rare appearance with Romney on Sunday. Democrat Tim Kaine, meanwhile, held a full slate of events in Hampton Roads Saturday ahead of the storm.

The storm could keep the presidential candidates out of Virginia until late next week, leaving them little time to campaign in one of the most important battleground states before the Nov. 6 election. That could undercut their get-out-the-vote efforts, which typically rely on candidate visits to rally the rank-and-file and stir enthusiasm ahead of Election Day, especially in states such as Virginia that have limited early voting.

Hurricane Sandy could further undermine voter turnout if cleanup efforts and power outages remain an issue on Election Day. Already, officials in some parts of the state have called for mandatory evacuations.

The Obama campaign is encouraging people to take advantage of in-person absentee voting, which the State Board of Elections is allowing for anyone affected by the storm.

Dominion Power sees restoring power to polling places as a top priority, right behind hospitals and water treatment plants, spokesman Karl Neddenien said.

"We understand the importance of supporting a good Election Day," Neddenien said.

Even as they were forced to scrap appearances, Obama and Romney were quick to convey a sense of concern for those in the path of the storm.

Romney's Virginia campaign has been temporarily converted to a storm relief effort, collecting donations to help with the storm's aftermath. Obama held a conference call with East Coast governors and mayors who will bear the brunt of the storm to reassure them of the federal government's support for their efforts.

Neither Obama nor Romney wants to be seen as politicizing the disaster, said Larry Sabato, director of the University of Virginia Center for Politics.

"If this is a serious storm and it has a serious impact, then Obama has an opportunity to look presidential for the tiny number of undecideds," said Sabato. "Or we could have foul-ups, which occur after disasters and put people in a sourly mood on Election Day."