BRIGANTINE, N.J. — President Barack Obama soberly toured the destruction wrought by Superstorm Sandy on Wednesday in the company of New Jersey’s Republican governor and assured victims “we will not quit” until cleanup and recovery are complete. Six days before their hard-fought election, rival Mitt Romney muted criticism of Obama as he barnstormed battleground Florida.

Forsaking partisan politics for the third day in a row, the president helicoptered with Gov. Chris Christie over washed-out roads, flooded homes, boardwalks bobbing in the ocean and, in Seaside Heights, a fire still burning after ruining about eight structures.

Back on the ground, the president introduced one local woman to “my guy Craig Fugate.” In a plainspoken demonstration of the power of the presidency, Obama instructed the man at the head of the Federal Emergency Management Agency, a 7,500-employee federal agency, to “make sure she gets the help she needs” immediately.

Despite the tour and Romney’s own expressions of sympathy for storm victims — a break on the surface from heated campaigning — a controversy as heated as any in the long, intense struggle for the White House flared over the Republican challenger’s new television and radio ads in Ohio.

“Desperation,” Vice President Joe Biden said of the broadcast claims that suggested automakers General Motors and Chrysler are adding jobs in China at the expense of workers in the bellwether state. “One of the most flagrantly dishonest ads I can ever remember.”

Republicans were unrepentant as Romney struggled for a breakthrough in the Midwest.

“American taxpayers are on track to lose $25 billion as a result of President Obama’s handling of the auto bailout, and GM and Chrysler are expanding their production overseas,” said an emailed statement issued in the name of Republican running mate Paul Ryan.

The two storms — one inflicted by nature, the other whipped up by rival campaigns — were at opposite ends of a race nearing its end in a flurry of early balloting by millions of voters, unrelenting advertising and so many divergent polls that the result was confusion, not clarity.

National surveys make the race a tight one for the popular vote, with Romney ahead by a statistically insignificant point or two in some, and Obama in others.

Both sides claim an advantage from battleground state soundings that also are tight. Obama’s aides contend he is ahead or tied in all of them, while Romney’s team counters that his campaign is expanding in its final days into what had long been deemed safe territory for the president in Michigan, Pennsylvania and Minnesota.

The storm added yet another element of uncertainty, as Obama spent a third straight day embracing his role as incumbent and Romney tried to tread lightly during a major East Coast disaster.

The president received a briefing at the Federal Emergency Management Agency across town from the White House before flying to New Jersey, where the shoreline absorbed some of the worst damage in a storm that killed 50 and laid waste to New York City’s electrical and transportation systems.

Christie was waiting when Air Force One landed, and he and Obama, two figures in blue windbreakers, walked together toward the president’s helicopter to begin their tour. It was a tableau that seemed impossible a week ago — a president struggling to defend his economic record in a tight election, flying off to a non-battleground state to spend the afternoon in the company of the man who delivered the keynote address at Romney’s Republican National Convention this summer.

Three hours later, the two men spoke of one another in glowing terms. “He has sprung into action immediately,” said Christie.

Said Obama of the governor, “He has put his heart and soul into making sure the people of New Jersey bounce back stronger than before.”

The storm forced an abrupt change in Romney’s campaign, as well.

In Tampa, the Republican challenger said, “We love all of our fellow citizens. We come together at times like this, and we want to make sure that they have a speedy and quick recovery from their financial and, in many cases, personal loss.” His criticism of Obama was glancing. “I don’t just talk about change. I actually have a plan to execute change and make it happen.”

The debate was ferocious over Romney’s broadcast ads. The radio version said that after Obama’s auto bailout, General Motors has “cut 15,000 American jobs, but they are planning to double the number of cars built in China which means 15,000 more jobs for China.

“And now comes word that Chrysler is starting to build cars in, you guessed it, China.”

Biden termed the ads scurrilous. He said that executives from General Motors and Chrysler, which produces Jeeps, had said the claims were inaccurate.

“Ladies and gentlemen, the truth is, just recently in the last couple of months, in Toledo, Ohio, not only is the Jeep plant open and churning out Jeeps, they announced they’re adding 1,100 new jobs.”