WASHINGTON >> Suddenly, after drifting through months of confusing finger-pointing and iffy economic theory, the presidential candidates are getting walloped by an all-too-tangible October surprise. Superstorm Sandy is a real-world, gut-level test.

The force of nature threw cold water on the campaign bickering just as President Barack Obama and Republican nominee Mitt Romney were charging into a final week of man-made rancor.

“It’s sort of like Mother Nature is intervening and calling a timeout,” said historian and presidential biographer Douglas Brinkley.

Obama can’t afford to be caught taking his eyes off an unfolding crisis. Romney needs to avoid appearing callous about the lives lost and homes flooded while campaigning; he decided to go on with events but dialed down the politics Tuesday.

Seven years after Hurricane Katrina, neither candidate wants to talk about the political implications of the giant storm that lurched up the East Coast and left millions without power.

But their campaigns have to think about it. All presidential teams sweat about the potential for an October surprise — a late-in-the race event or disclosure that can turn the race upside down. And there’s never been one quite like this.

Obama canceled his campaign appearances from Monday at least through Wednesday but is staying in the public eye as commander of federal relief efforts. He visited the American Red Cross headquarters on Tuesday and travels to New Jersey on Wednesday to view damage and comfort people recovering from the storm.

Romney wavered in his strategy. First the campaign said he would skip a Kettering, Ohio, rally Tuesday out of sympathy for the storm victims. Then Romney decided to do the event but recast it as a storm-relief effort, shorn of the usual campaign speech.

“It’s part of the American spirit, the American way, to give to people in need,” Romney told supporters in Kettering before they lined up to hand him bags of canned food for storm victims.

Romney planned three campaign events in Florida on Wednesday.

The storm’s political impact is still unknown. At the very least, the aftermath in New York City and elsewhere will dominate the news and distract a nation of voters during the crucial handful of days that remain before Nov. 6.

More concrete effects on Election Day are yet to be tallied: how many early voting days lost, how many voters who don’t make it to the polls because of power outages, damaged homes or cleanup duties, whether any polling places or election equipment are damaged. Parts of four states seen as pivotal to this election were hit — North Carolina, Virginia, Ohio and New Hampshire.

Though rapid-fire campaign ads continue apace, Brinkley, a Rice University professor, predicted that the presidential race’s less-strident tone will continue through its remaining week, even after campaign schedules return to full strength.

“When the nation’s largest city and even its capital are endangered, when so many people are in peril and face deprivation,” Brinkley said Monday, “it’s hard to get back to arguing over taxes.”

For Obama, the federal response to the natural disaster could make or break his bid for a second term. Romney risks losing momentum in his push to move ahead in the few tight state races expected to decide the election.

“It stops the campaign more or less dead in its tracks,” said Republican pollster and strategist Mike McKenna, who doesn’t work for the Romney campaign. “A pause always helps the guys on defense. It helps the Obama guys catch their breath a little bit and think about what to do next.”

McKenna says Romney shouldn’t take much time off and should instead focus on key states outside the storm zone.

“If I were Romney, I’d be in Colorado and Michigan and Wisconsin,” McKenna said. “Start off with a prayer for the people in New York and New Jersey, definitely do that, but don’t stop attacking. Try to keep your momentum through this.”

For Obama, missing a few days of active campaigning for vital presidential duties may be a good trade, politically speaking.

Lingering anger about the previous president’s performance when Hurricane Katrina struck New Orleans provides a backdrop that will benefit Obama if his administration does a solid job, said Kathleen Hall Jamieson, director of the University of Pennsylvania’s Annenberg Public Policy Center.

“You gain much more as a president being contrasted with George W. Bush and Hurricane Katrina than you do giving a speech in some battleground state and getting on the evening news as a campaigner,” Jamieson said.

She said a natural disaster gives a sitting president “unlimited access to the media to say things the public wants and needs to hear in a fashion that reinforces that he is president.”

The 2008 election also was hit by a fall surprise, albeit one of human creation— the plummeting stock market and near collapse of the nation’s financial sector that September. Many voters blamed that on the Republicans in power, and it helped Obama capture the presidency.

This time, neither candidate can be accused of failing to prevent the weather. But Obama’s reputation will suffer if the federal government’s response is feeble or botched.

With Election Day a week away, there may be little time to make such assessments, however, and a risk of appearing to politicize tragedy if Romney speaks up too soon — a complaint that Democrats lodged against him when a U.S. Consulate in Libya was attacked.

“Criticism could boomerang if it appears to be ginned up to win votes in the election as opposed to genuine concern that people were not protected or people were not helped,” said Mitchell McKinney, a professor of political communication at the University of Missouri.

For the former Massachusetts governor, with no political office as a platform, finding a strong, positive role in the storm response is difficult. Romney used a campaign event Monday at a high school gym in Avon Lake, Ohio, to make a plea for donations to the Red Cross. His campaign offices in storm-hit areas were collecting emergency supplies.

Even as Obama canceled an appearance in Florida on Monday and rushed back to Washington to oversee the storm response, first lady Michelle Obama and Vice President Joe Biden kept campaigning.

“In times of crisis, we all pull together as one American family,” Mrs. Obama told supporters at a campaign event in Iowa City, Iowa, before launching into an upbeat summation of her husband’s accomplishments and goals.

The president and Romney also spoke of Americans helping each other.

“President Obama is doing the right thing. Romney, too,” said Democratic Party strategist Donna Brazile. “Most Americans know what the closing arguments are by now. Let’s focus on taking care of each other.”