ST. PAUL, Minn. — Senator McCain tore up the script for his Republican National Convention today, canceling most opening-day activities and positioning himself as above mere politics as Hurricane Gustav churned toward New Orleans.

“This is a time when we have to do away with our party politics and we have to act as Americans,” he said as fellow Republicans converged on their convention city to nominate him for the White House.

On the eve of his convention, Mr. McCain took on the role of a concerned potential president determined to avoid the errors made by President Bush three years ago. “I have every expectation that we will not see the mistakes of Katrina repeated,” he said.

Mr. Bush and Vice President Cheney scrapped plans to address the convention today, and Mr. McCain’s aides chartered a jet to fly delegates back to their hurricane-threatened states along the Gulf Coast. His campaign manager, Rick Davis, said the first-night program was being cut from seven hours to two and one half.

Mr. McCain said in an interview with NBC that it was possible he would make his acceptance speech not from the convention podium but via satellite from the Gulf Coast region.

The formal business of the convention includes nominating Mr. McCain for president and Governor Palin of Alaska as his vice presidential running mate on Wednesday. Mr. McCain’s acceptance speech, set for prime time on Thursday evening, is among the most critical events of the campaign for his chances of winning the White House.

The hasty reordering of an event months in the planning was unprecedented, affecting not only the program on the podium but the accompanying fundraising, partying, and other political activity that unfolds around the edges of a national political convention.

Mr. McCain said he was looking forward to being at the convention but did not say when he would arrive. He spoke from St. Louis after he and Ms. Palin received a briefing on hurricane preparations on a quick visit to Jackson, Miss.

Democratic rival Senator Obama got a briefing, too, by telephone from the Homeland Security Secretary, Michael Chertoff. Mr. Obama heard about the status of the storm, the evacuation effort, and coordination between federal, state, and local authorities, according to a Democratic campaign adviser, Robert Gibbs.

The McCain campaign manager, Mr. Davis, told reporters inside the convention hall that the opening program tomorrow would be “business only and will refrain from political rhetoric.”

To help those in need, he said, “We are working with the delegations, financial people, finance committees, many other concerned individuals to do what we can to raise money for various charities that operate in the Gulf Coast region.”

As for the convention schedule, he added that further adjustments would be made on a day-to-day basis.

Mr. McCain said of his briefing in Mississippi: “I’m happy to report to you that the coordination and the work that’s being done at all levels appears to be excellent.” He cited remaining challenges in communications and search and rescue operations, but emphasized that the response seemed to be going more smoothly than the one three years ago.

The Bush administration’s handling of that storm contributed to a plunge in the president’s approval ratings that helped the Democrats win control of Congress in 2006.

The uncertainty contrasted with a state of readiness inside the Xcel Center, a hockey arena transformed into a made-for-televison red-carpeted convention hall. Thousands of red, white, and blue balloons nestled in netting high above the floor — to be released during final-night festivities if the Republicans decide to go ahead with them.

Outside, police took nine people into custody for crossing a security barrier in an anti-war march. The nine, including two women in their 70s, were charged with trespassing, according to a St. Paul police commander, Doug Holtz.

Emphasizing their concern about the hurricane, Mr. McCain and his newly named running mate traveled to Mississippi for a tour of the state’s emergency management center.

“I pledge that tomorrow night, and if necessary throughout our convention, we will act as Americans, not as Republicans,” Mr. McCain told reporters moments later.

The events temporarily overshadowed a more traditionally political pre-convention debate over Mr. McCain’s decision to name Ms. Palin to his ticket. She was mayor of small-town Wasilla, Alaska, for six years before she became governor in December 2006.

Responding to a question after his hurricane-related remarks, Mr. McCain made a ringing defense of Ms. Palin, who Democrats argue has less experience than their presidential candidate, Mr. Obama.

“I think Senator Obama, if they want to do down that route, in all candor, she has far, far more experience than Senator Obama does,” Mr. McCain said.

He cited Ms. Palin’s stint as governor of a “state that produces 20 percent of America’s energy” as well as her previous membership in the PTA and her time spent on the city council and in the mayor’s office in Wasilla,a town of fewer than 7,000 people outside Anchorage.

By contrast, he said Mr. Obama “was a community organizer when she was in elected office. He was in the state Senate and voted 130 times present. He never took on his party on anything. She took on a party and the old bulls and the old boy network and she succeeded.”

Ms. Palin has frequently clashed with fellow Republicans in her state, and won office after denying an incumbent GOP governor renomination to a new term in office.

But Senator Dodd, a Democrat of Connecticut, said Mr. McCain’s selection was merely designed to appease the hard-right conservatives in the Republican Party. “His knees buckled” when it came time to picking a running mate, Mr. Dodd said of Mr. McCain in an appearance on CNN.

Democrats, too, decided to tone down their convention-week efforts.

A party spokesman, Brad Woodhouse, said the Democrats had canceled a “More of the Same” rally that had been slated for tomorrow.

Mr. Obama said he was ready to encourage his supporters to assist any victims of the hurricane.

“I think we can activate an e-mail list of a couple of million people who want to give back,” he said.

With millions of Gulf Coast residents fleeing the approaching storm, a delegate from Baton Rouge, Chadwick Melder, said he was taking advantage of an offer from the campaign to fly his family out of harm’s way.

“I’m trying to get my family out of there and stay here for the week,” Mr. Melder said, although he added, “I have responsibilities here as well.”