Republican presidential hopeful Mitt Romney pledged bipartisanship before early voters in Florida on Saturday while President Barack Obama worked to nail down tiny New Hampshire's four electoral votes ahead of the Nov. 6 election.

Both campaigns scrambled to steer clear of a most unlikely October surprise, a superstorm barrelling up the East Coast.

On Saturday night, the White House announced Obama had cancelled campaign appearances in Virginia on Monday and Colorado on Tuesday so he can monitor Hurricane Sandy. Romney scrapped plans to campaign in Virginia on Sunday, and switched his schedule for the day to Ohio.

Vice President Joe Biden cancelled a Saturday rally in coastal Virginia Beach, Va., to allow local officials there to focus on disaster preparedness and local security concerns. But he went ahead with an appearance in Lynchburg, which is inland

Romney, who has pivoted away from earlier ultra-conservative messages to strike a moderate tone in a bid to win votes from women and independents, campaigned across Florida on Saturday with a pledge to "build bridges" with Democrats.

He coupled that message with digs at Obama for advancing an agenda that lacks vision. Noting that Obama supporters like to chant "four more years" at the president's campaign rallies, Romney picked up on his crowd's own chant at the Pensacola Civic Centre and said: "I like '10 more days' a lot better.'"

Senator Marco Rubio told the crowd that Obama was advancing "the ideas of countries that people come here to get away from." Pressed later on what countries he was referring to, the Florida Republican said, "any big-government country in the world" and specifically referred to Mexico and Latin America.

Electoral arithmetic

In New Hampshire, Obama told volunteers at a Teamsters hall in Manchester that: "We don't know how this thing is going to play out. These four electoral voters right here could make all the difference."

It takes 270 electoral votes to win the election. Obama is ahead in states and the District of Columbia representing 237 electoral votes; Romney has a comfortable lead in states with 191 electoral votes. The rest lie in nine contested states that are too close to call, New Hampshire among them.

The president adjusted his campaign speech at a Nashua rally to appeal to voters in low-tax New Hampshire, hammering Romney for raising taxes and fees as governor of neighbouring Massachusetts. Obama accused Romney of running in Massachusetts on a pledge to lower taxes, then making life more expensive for the middle class after taking office.

"All he's offering is a big rerun of the same policies," Obama told a crowd of 8,500 gathered at an outdoor rally on an unseasonably warm October day.

The candidates worked to lock down every possible early vote without intruding on emergency preparations as the storm's expected track looked to affect at least four battleground states: North Carolina, Virginia, Ohio and New Hampshire.

Ryan stumps in Ohio

Romney's running mate, Rep. Paul Ryan, worked his way across rainy, chilly Ohio, on a two-day bus trip, with his family in tow. At a factory in New Philadelphia, Ryan stressed the hit that manufacturing industries have taken over the last four years and promised more coal jobs, natural gas jobs and increased military spending if Romney is elected.

En route to New Hampshire, Obama held an airborne conference call with administration officials about the federal government's role in minimizing storm damage and a ensuring speedy recovery effort.

Campaign spokesman Jennifer Psaki said the Obama team was continuing to promote early voting as something that provides flexibility for busy families, but she added that with the storm headed for shore, "safety comes first, and that's the case with early voting as well."