Scrambling to avoid the superstorm that threatens to disrupt the lives of millions of Americans up and down the East Coast, Republican Mitt Romney is returning to battleground Ohio to fight for momentum nine days before the election.

The GOP presidential candidate had planned to campaign Sunday in Virginia, but will instead join running mate Paul Ryan in the Buckeye State. The weather also forced President Barack Obama to shift his campaign schedule.

The storm presents both sides with a most unlikely October surprise as polls show an extraordinarily tight race. Hurricane Sandy had each campaign discarding carefully mapped-out itineraries as they worked to maximise voter turnout while avoiding any suggestion they were putting politics ahead of public safety.

On Saturday, Romney spoke of bipartisanship before early voters in Florida, while Obama worked to nail down tiny New Hampshire's four electoral votes.

The former Massachusetts governor, who presented himself as a staunch conservative during the Republican primaries but has been striking a more moderate tone as he courts women and independent voters in the campaign's home stretch, campaigned across Florida. He promised to "build bridges" with Democrats.

Romney coupled his message with digs at the president for "shrinking from the magnitude of the times" and advancing an agenda that lacks vision.

Obama, who planned to travel to Florida Sunday night, took his campaign to New Hampshire. He told volunteers Saturday 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."

Winning the White House takes 270 electoral votes. 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 remain too close to call.

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 neighboring 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.

Nature’s fury

* Hurricane Sandy set to make history as it aims at US coast
* Sandy expected to come ashore Monday night
* Sandy's large wind field a record maker
* Storm may halt, flood New York City subway system