(CNN) -- Sen. John McCain blasted the Bush administration and all levels of government Thursday for the failed response to Hurricane Katrina in New Orleans.
"We know we didn't have the right kind of leadership ... where government agencies were getting information from watching cable television rather than have a flow of information," McCain said during an event at Xavier University in New Orleans.
"It was not only a perfect storm as far as its physical impact ... it was a perfect storm as far as the federal, state and local governments' inability."
"Never again will there be a mismanaged natural disaster," he said, later assuring the crowd that "it will never happen again in this country; you have my commitment and my promise." Watch a report on McCain's tour and criticism »
McCain cited numerous mistakes made by Bush, including his initial decision to fly over the area soon after the storm rather than stop for a visit.
Bush endorsed McCain for president the day after the GOP nomination was sealed in March. McCain said then that he wanted Bush at his side as much as possible on the campaign trail.
McCain was in New Orleans on the fourth day of a tour through some Democratic strongholds in economically struggling states, trying to convince voters that he's not the typical Republican.
He made stops this week in Selma, Alabama; Youngstown, Ohio; and Inez, Kentucky.
The Arizona senator toured New Orleans' 9th Ward, the neighborhood hit hardest by Hurricane Katrina, and discussed the tough times ahead for the poverty-stricken area.
"We ... know that there's enormous challenges ahead," McCain said. "Americans have not forgotten New Orleans."
McCain and his wife, Cindy, along with Republican Gov. Bobby Jindal, spent about 20 minutes walking through the Lower 9th, stopping at a house being rebuilt by about a dozen volunteers from DeutscheBank in New York.
"I'm proud to be in your company. You're what America's all about," McCain told them.
McCain also visited with workers at the Lower 9th Ward Neighborhood Empowerment Association. He asked Leroy Crawford how things were going; "It's work, but we're working," Crawford replied. Watch more on McCain's visit to New Orleans »
One official took issue with McCain's behavior after Katrina. In a statement issued Thursday, Howard Dean, chairman of the Democratic National Committee, blasted him for "hiding" from votes against Katrina legislation, like unemployment assistance and emergency health care for survivors.
McCain responded by saying the bills were partisan and pork-laden, and saying the way to help is to have Washington fix its priorities.
In addition to touring, McCain is trying to put out a political fire set by members of his own party: a controversial ad that he opposed slamming Democratic candidate Sen. Barack Obama that is running in North Carolina.
After McCain effectively clinched the Republican nomination, he called on his party to run a respectful, above-the-fray campaign.
But the ad, conceived by North Carolina Republicans, appears to defy that call.
"For 20 years, Barack Obama sat in his pew listening to his pastor," the TV ad says.
The ad then airs comments from Obama's pastor, the Rev. Jeremiah Wright, who says: "And then wants us to sing 'God Bless America?' No, no, no. Not 'God Bless America,' God [expletive] America."
McCain's campaign released an e-mail he sent North Carolina GOP Chairwoman Linda Daves that asked her not to run the ad.
"In the strongest terms, I implore you to not run this advertisement," he wrote. "This ad does not live up to the very high standards we should hold ourselves to in this campaign."
North Carolina Republicans refused to pull the ad.
"I can't dictate to them. But I want to be the candidate of everybody. I want to be the candidate of Republicans and Democrats and independents," he said Wednesday. Watch McCain's response to the ad »
During one New Orleans appearance, an audience member questioned McCain about an endorsement he received from controversial Pastor John Hagee, who once said on a radio show that "what happened in New Orleans looks like the curse of God."
"When someone endorses me, [it] does not mean I embrace their views," he responded. Later on his bus, McCain elaborated, "I didn't attend pastor Hagee's church for 20 years."
Even as McCain promised to stick to issues, he found an opportunity to knock Obama for remarks that suggested rural and working-class voters, bitter about the economy, focus on issues involving religion and guns.
"Those are elitist remarks, to say the least," McCain said. E-mail to a friend
CNN correspondent Dana Bash contributed to this report.