NEW ORLEANS — Finally a hurricane, the unwieldy and wobbly Isaac bore down on New Orleans Tuesday, almost seven years to the day that Hurricane Katrina transformed this city and became a symbol of government ineptitude, and a defining moment for leaders from City Hall to the White House.

While Isaac was far less powerful than the 2005 storm, it posed some of the same political challenges. President Barack Obama sought to demonstrate his ability to guide the nation through a natural disaster and Republicans reassured residents they were prepared, all the while readying for the coronation of Mitt Romney.

In New Orleans, the mood was calm as the first wave of rain bands and wind gusts rolled ashore, and these battle-tested residents took the storm in stride, knowing they’ve been through a lot worse. Tens of thousands of people, mostly in southeastern Louisiana, were ordered to evacuate ahead of Isaac, which was set to make landfall Tuesday night as a Category 1 hurricane with winds of at least 74 mph — much lower than the 135 mph winds Katrina packed in 2005.

About 13,000 homes and businesses had already lost power Tuesday afternoon. The storm’s winds increased slightly to 80 mph as it closed in on the coast.

Many residents along the Gulf Coast opted to ride it out in shelters or at home and officials, while sounding alarm about the dangers of the powerful storm, decided not to call for mass evacuations. Still, there was a threat of storm surge and the possibility of nearly two feet of rain as it slowly trudges inland.

“We don’t expect a Katrina-like event, but remember there are things about a Category 1 storm that can kill you,” Mayor Mitch Landrieu said, urging people to use common sense and to stay off any streets that may flood.

There was already simmering political fallout. Republican Gov. Bobby Jindal, who canceled his trip to the Republican National Convention in Tampa, Fla., said the Obama administration’s disaster declaration fell short of the federal help he had requested. Jindal said he wanted a promise from the federal government to be reimbursed for storm preparation costs.

“We learned from past experiences, you can’t just wait. You’ve got to push the federal bureaucracy,” Jindal said.

FEMA Administrator Craig Fugate said such requests would be addressed after the storm.

“We wanted to make sure direct federal assistance got out first,” Fugate said.

Obama, during a campaign stop in Iowa, attempted to stay above the fray.

“America will be there to help folks recover no matter what this storm brings. Because when disaster strikes, we’re not Democrats or Republicans first, we are Americans first,” the president said.

Isaac became a hurricane Tuesday, a massive storm that reached more than 200 miles from its center, threatening to flood the coasts of four states with storm surge and heavy rains on its way to New Orleans.

At businesses near the French Quarter, windows were boarded up and sandbags were stacked a few feet high in front of doors.

Some tourists said they would ride out the storm near the city’s famed Bourbon Street, and there was little to suggest a sense of worry.

“We made it through Katrina, we can definitely make it through this. It’s going to take a lot more to run me, I know how to survive,” he said.

Obama said Gulf Coast residents should listen to local authorities and follow their directions as Isaac approached.

“Now is not the time to tempt fate. Now is not the time to dismiss official warnings. You need to take this seriously,” Obama said.

In Houma, a city southwest of New Orleans, people filled a municipal auditorium-turned-shelter. However, in the bayou country of Terrebonne Parish off Highway 24, storms pose a perennial dilemma for those living a hardscrabble life.

While some of the homes along Bayou Terrebonne and other nearby waterways show signs of affluence, this section of Louisiana 24 is mostly lined with trailer homes or small, often run-down houses. Staying could be dangerous, but many here who could be in harm’s way have nowhere to go and little money to get there, especially given the high price of gasoline.

Monica Boudreaux lives in a trailer on low-lying land but was talking Tuesday morning with a cousin who lived closer to the bayou. They and two friends chatted as the storm approached. Boudreaux laughed when asked what she’ll do if the storm hits.

“I’m surrounded by all family,” she said, referring to her friends as well as her cousin. “I’ll just pick up my little fat feet and run, I guess.”

Water may be worse than wind because the storm could push walls of water while dumping rain to flood the low-lying coast in Louisiana, Mississippi, Alabama and the Florida Panhandle.

New Orleans is in much better shape than it was before Katrina with an injection of about $14 billion in federal funds to fix damage done by Katrina and upgrade the system.