Obama's visit was pre-empted by his Republican challenger, Mitt Romney, who diverted from the campaign trail to Louisiana on Friday to inspect the fallout from Hurricane Isaac a day after accepting his party's nomination for the November 6 election.
Flying into New Orleans on a hot, sunny day, Obama traveled by motorcade to nearby St. John the Baptist Parish, one of the hardest-hit communities, where he met federal, state and local officials and then surveyed the area.
He saw evidence of the storm's fury - twisted road signs, toppled trees, blown-down fences, debris piled high and pools of water beside the road. Stepping out of his limousine, he paused to comfort a few residents and hear their stories.
"There has been enormous devastation in St. John's Parish," Obama told reporters. He cited similar destruction in other parts of Louisiana as well as neighboring Mississippi and praised emergency officials for limiting the loss of life.
The White House has taken pains to depict Obama as deeply engaged in the government's handling of Isaac and its aftermath. His Republican predecessor, George W. Bush, was heavily criticized for the sluggish federal response to Hurricane Katrina, which devastated New Orleans in 2005.
Being cast in the role of consoler-in-chief could have political benefits for Obama, who is locked in a tight race with Romney and will accept his party's nomination in a prime-time speech on Thursday night in Charlotte, North Carolina. The convention begins on Tuesday.
"How y'all doin'?" Obama asked Trebor Smith, wearing shorts and high rubber boots, outside his storm-damaged house.
"Better now," Smith said.
One woman told Obama the water rose so fast that she and her family had to rescued by boat.
Isaac was the first hurricane to strike the United States this year, hitting New Orleans almost exactly seven years after Katrina hit, causing an estimated 1,800 deaths.
But Isaac was a much weaker storm. It was blamed for six deaths in Louisiana and two in neighboring Mississippi, and both states suffered from widespread flooding.
ABOUT 125,000 STILL WITHOUT POWER
Even as the fading remnants of Isaac moved east, about 125,000 people remained without power in Louisiana, the governor's office said. With floodwaters not yet receded in some areas, about 2,600 people remained in emergency shelters. Obama has declared disasters in Louisiana and Mississippi.
Isaac's passage through the Gulf of Mexico last week forced cancellation of one day of the Republican convention in Tampa, Florida, and took some attention away from it.
Obama, staying away from the region while emergency officials were occupied with the height of the crisis, waited until Monday for his visit. He went ahead with a Labor Day rally with union workers in Ohio but freed up time in his campaign schedule by scrapping a second event in the battleground state.
Romney, a wealthy former private equities executive who has struggled to show that he can connect with ordinary Americans, detoured to the disaster zone the day after his convention.
Obama, overheard by news photographers allowed in for a few minutes while he was being briefed, said such presidential visits to disaster zones were "not just for photo-ops."
The White House sought to play down any political implications of the two visits at the height of election season, and highlighted the fact that Louisiana's Republican governor, Bobby Jindal, accompanied both of the men.
But White House spokesman Jay Carney, speaking to reporters aboard Air Force One, echoed Democrats who have pointed out that Romney's running mate, congressional fiscal hawk Paul Ryan, had earlier proposed sharp cuts in disaster relief spending.
" Our biggest priority is helping to house people who've been displaced ... to make sure they have the kind of support they need to get restarted," Obama said on the ground.
He made a point of praising the Federal Emergency Management Agency, saying "in the past we haven't seen the kind of coordination that is necessary." FEMA was a focus of criticism for what was seen as the botched response to Katrina in 2005.
Obama also hailed the first successful test of New Orleans' new $14.5 billion flood defenses, a reinforced network of government-built levees. But he said flooding in St. John the Baptist Parish and elsewhere showed the need for further work and pledged federal efforts to find out what went wrong and expedite solutions.
Meantime, oil operations that had been interrupted along the Gulf Coast were coming back on line. The Energy Department said the Exxon Mobil Corp's joint-venture 192,500 barrel per day (bpd) Chalmette, Louisiana, refinery was restarting on Monday.
The department also said Exxon's 502,500 bpd Baton Rouge refinery has returned to normal production after reducing throughput because of Isaac. Only Phillips 66's 247,000 bpd refinery in Alliance, Louisiana, remained shut on Monday due to flooding and power loss from the storm, the agency said.
