New York-Mary Wittenberg, chief executive of New York Road Runners, defended the decision to put on the New York City Marathon as scheduled Sunday after some runners and politicians called for the race to be canceled in the wake of Hurricane Sandy.

“This isn’t about running, this is about helping the city,” Wittenberg said Thursday morning at the Jacob K. Javits Center, where runners were starting to register for the race. “We’re dedicating this race to the lives that were lost and helping the city recover. We want to raise money and awareness.”

Before the hurricane, Road Runners was expecting to raise about $34 million for about 300 charities. Wittenberg said this year’s race could be used as a platform for charities that would directly help people affected by the storm.

Mayor Michael R. Bloomberg, who supports the marathon partly because it generates hundreds of millions of dollars in economic activity, repeated Thursday that he expected the race to be held. Wittenberg said Wednesday that the decision to run the race was ultimately his.

Despite criticism to the contrary, the mayor said he did not expect the police department to be overly burdened because the race was on a Sunday, when street traffic is at a minimum. Many parts of the city, including Lower Manhattan, are expected to have their power back, freeing up other workers.

“The city is a city where we have to go on,” Bloomberg said at a news conference Thursday afternoon.

Clearly, though, not everything is going on. Wittenberg said that preparations for the 26.2-mile course “are going well,” but that Road Runners had “essentially canceled” all of its other events before the marathon, including a youth event Thursday, the opening ceremony in Central Park on Friday and the Dash to the Finish Line 5K on Saturday that would have run through Midtown.

Wittenberg said Road Runners had cancellation insurance, which most likely would have covered the cost of refunding entry fees and other items had the race been called off.

Bloomberg said parks, including Central Park, where the marathon’s finish line is situated, would reopen this weekend. Road Runners took down several facilities it had built in the park, and those will need to be rebuilt.

Many of the elite runners in the marathon typically train there in the days before the race. Several of them have worked out in gyms or on the indoor track at the Armory on 168th Street.

Airports and rail service are gradually resuming service, which means many runners have yet to reach the city. Once they do, other accommodations will be needed. The Staten Island Ferry transportation option to the start line has been canceled, according to the marathon’s Web site, and runners who selected that service have been reassigned to bus service from the New York Public Library at 42nd Street and Fifth Avenue. About half of the 47,000 runners in the marathon usually take that route to the start line at the toll plaza to the Verrazano-Narrows Bridge in Staten Island.

Some politicians, including James P. Molinaro, the borough president of Staten Island, and Liz Krueger, a state senator who represents part of Midtown, have criticized the mayor’s decision to continue with the race. Some runners have said they will not run this year because of the burden it would cause.

Clearly, many runners in the race are eager to run. In New York on Thursday morning, hundreds of them picked up their bibs at the Javits Center. Upstairs, exhibitors’ booths lined the cavernous convention hall where the heavy-metal anthem “Rock You Like a Hurricane” was playing on the audio system.

Downstairs from the health and fitness show, workers were cleaning up the water-damaged floor, which emitted a faint stale water odor that wafted with the brew of a nearby Starbucks outpost.

“It’s safe,” Alan Steel, president and chief executive of the Javits Center, said, adding that the floor where the exposition was taking place was “entirely separate from where the water damage was.”

Exhibitors who usually have days to set up had just hours, some working late Wednesday or arriving early Thursday. Lt. Larry Quinn of the New York Firefighters Burn Center Foundation said he left Long Island at 5:30 Thursday morning and arrived at the Javits Center at 9 a.m. to unpack cardboard boxes of T-shirts, sweatshirts and baseball hats for sale. The proceeds go to the charity, which supports treatment for burn victims and research.

“We got guys sleeping on cots and working long hours,” Quinn said. “A lot of firemen live in Breezy Point and their homes are gone.”

He paused, holding a T-shirt in his hand: “But we’re a nonprofit. We need the money that we raise here for the foundation. We support the marathon.”

Some of the runners at the expo said they, too, felt committed to the race, regardless of the storm. Jessica Stephens and Kirsty Murfitt arrived from Wellington, New Zealand, last Friday, part of their existing plans to spend time in the city before the marathon sightseeing.

“We wanted to do New York because it’s the biggest and the best,” Stephens said. “We were here and we can see the storm was very, very serious. At the same time, people spend a lot of money at the local businesses here and New Yorkers have a can-do attitude.”