Hundreds of miles away, Romney said he was concerned for the safety of those who "are going to be affected" by the storm, which is predicted to worsen into a hurricane as it heads for landfall along the Gulf Coast.
In a presidential race defined by its closeness, Republican office-holders past and present said the party must find a way to appeal to women and Hispanics, and they said the economy was the way to do it.
"We have to point out that the unemployment rate among young women is now 16 percent, that the unemployment rate among Hispanics is very high, that jobs and the economy are more important, perhaps, than maybe other issues," said Arizona Sen. John McCain, who lost to Obama in 2008.
Former Florida Gov. Jeb Bush agreed, saying that Romney "can make inroads if he focuses on how do we create a climate of job creation and economic growth." If he succeeds, "I think people will move back towards the Republican side," Bush added.
Obama leads Romney among women voters and by an overwhelming margin among Hispanics, but he trails substantially among men.
The result is a race that is unpredictably close, to be settled in a small number of battleground states.
An estimated $500 million has been spent on television commercials so far by the two candidates, their parties and supporting outside groups, nearly all of it in Florida, North Carolina, Virginia, New Hampshire, Ohio, Iowa, Colorado and Nevada. Those states account for 100 electoral votes out of the 270 needed to win the White House.
Republicans have made no secret that they are eager to expand the electoral map to include Pennsylvania, Michigan, perhaps running mate Paul Ryan's Wisconsin and even Minnesota, states with 68 electoral votes combined.
All four are usually reliably Democratic in presidential campaigns. Yet Romney has a financial advantage over the president, according to the most recent fundraising reports, and a move by the Republicans into any of them could force Obama to dip into his own campaign treasury in regions he has considered relatively safe.
Making his case for the support of female voters, Romney said in the Fox interview: "'Look, I'm the guy that was able to get health care for all of the women and men in my state. ... 'I'm very proud of what we did."
It was a rare voluntary reference to the legislation he signed as governor of Massachusetts that required the state's residents to purchase coverage, the sort of mandate that is at the heart of Obama's federal legislation that conservatives oppose and Romney has vowed to see repealed.
Romney added that the state law was put into place "without cutting Medicare, which obviously affects a lot of women."
That was a reference to the federal law, which cut more than $700 billion in projected Medicare costs to help provide health care to millions who could not otherwise afford it.
Medicare generally favors Democrats as a political issue, but Romney has aggressively sought to cut into that advantage. He released a new television ad criticizing Obama's handling of the program with a catchphrase of "It ain't right."
The streets around the convention hall were crowded with police, National Guard and other security officials, who manned checkpoints in squads rather than individually.
A few hundred protesters gathered in a park about a half-mile from the convention vowed to make their point regardless of Tropical Storm Isaac. They set out large blocks of ice spelling out the words "middle class," and left them to melt on a warm, humid day, a gesture meant to signify middle class disappearance in a tough economy.
Bush and McCain were interviewed on NBC, and Priebus spoke on CNN.
Associated Press writers Tamara Lush and Brendan Farrington in Florida, Steve Peoples in New Hampshire, Philip Elliott in Wisconsin and Alicia Caldwell in Washington contributed to this story.