(CNN) -- After his infamous "brain freeze" that drew laughter and ridicule from his detractors, Texas Gov. Rick Perry poked fun at himself Thursday night while delivering the "Top Ten" list on CBS' "The Late Show with David Letterman."
Perry sauntered on stage smiling, clapped his hands and saluted the crowd before rattling off the "Top Ten Rick Perry Excuses." Among them:
No. 6: "You try concentrating with Mitt Romney smiling at you. That is one handsome dude!"
No. 5: "Uh, El Nino?"
No. 4: "I had a 5-hour Energy drink six hours before the debate."
No. 2: "I wanted to help take the heat off my buddy Herman Cain."
No. 1: "I just learned Justin Bieber is my father."
Perry made sure he was in control of the jokes after Wednesday's GOP debate in Rochester, Michigan, when he said he would eliminate three federal agencies if elected president -- but could name only two of them.
That produced a painful period of more than 50 seconds during which Perry tried in vain to remember the third federal agency. It ended only after Perry conceded that he could not remember it -- even after appearing to consult his notes.
"Oops," he said.
Perry has a chance to redeem himself on the debate front Saturday, when he is scheduled face off with other Republican presidential hopefuls at the CBS News-National Journal debate in South Carolina.
The morning after the debacle, Perry said his "brain freeze" showed he is not "the slickest politician" among the field of Republican presidential hopefuls.
His campaign, meanwhile, sought to raise funds off the gaffe, encouraging supporters to send $5 for every government agency they "would like to forget."
Operatives from the left and the right slammed the moment as a potential sign of Perry's campaign imploding. The New York Times quoted Mark McKinnon, an aide to former President George W. Bush, as calling the moment the "human equivalent of shuttle Challenger."
Speaking to CNN's Christine Romans on Thursday, Perry said, "we need substance more than we need style" and tried to turn the incident into an attack on President Barack Obama.
When Romans said that the president has to be "debater in chief," Perry responded, "We've got a debater in chief right now. And you've got to ask yourself: How's that working out for America?"
His campaign sent out a note to supporters saying, "We've all had human moments."
The note from "Team Perry" points out that Obama, at a campaign stop during the 2008 election, referred to having visited "57 states."
"Ronald Reagan got lost somewhere on the Pacific Highway in an answer to a debate question," the note adds. "Gerald Ford ate a tamale without removing the husk. And tonight Rick Perry forgot the third agency he wants to eliminate. Just goes to show there are too damn many federal agencies."
In a 1984 debate against Walter Mondale, then-President Reagan delivered a closing statement that was widely viewed as rambling. He began by describing a day he had driven down the California coast. Reagan had to be cut off by the moderator. Ford, in 1976, was meeting voters in Texas when he bit into a tamale. Unaware of how to eat it, he did not first remove the husk.
At Wednesday's debate, Perry was facing Texas Rep. Ron Paul when he started to answer the question.
"I will tell you, it is three agencies of government when I get there that are gone," Perry said. "Commerce, Education, and the -- what's the third one there? Let's see. OK. Commerce, Education, and the ... "
"EPA?" Mitt Romney offered.
"EPA, there you go," Perry said.
When pressed by moderator John Harwood if the Environmental Protection Agency was indeed the third agency he proposes shuttering, Perry admitted that it wasn't. He then attempted again to remember the details from his plan.
"The third agency of government I would -- I would do away with Education, the Commerce, and, let's see. I can't. The third one, I can't. Sorry. Oops."
Several minutes later, Perry clarified that the agency he was trying to remember was the Department of Energy.
Perry was already saddled with a series of lackluster debate performances and is down in the polls.
On Twitter, reaction was swift.
"Perry collapses. Cannot remember a list of three federal government departments he wants to abolish past the first two. Seriously. And then he says 'oops.' He has all but disappeared inside his suit in this debate and is now basically done," conservative blogger Andrew Sullivan tweeted.
Democratic strategist and CNN contributor Roland Martin exclaimed, "Damn, he actually forgot the third federal agency he would get rid of! That is THE MOST EMBARRASSING moment of any debate I've seen!"
Appearing in the spin room after the debate, Perry tried to make light of the gaffe.
"I'm sure glad I had my boots on," he said, "because I sure stepped in it out there."
CNN's Kevin Liptak, Josh Levs and Peter Hamby contributed to this report.