"Oh, shoot, no," Perry told The Associated Press on Thursday morning, the day after making the error during a GOP debate. Asked whether his campaign, which is struggling to regain traction, could survive, Perry replied: "This ain't a day for quitting nothing."
Perry says others have made similar mistakes and that the screw-up will humanize him. "The president of the United States said there were 57 states one time. Everybody makes mistakes," Perry said.
During a May 2008 campaign stop in Beaverton, Ore., then-candidate Barack Obama said he had spent the past 15 months visiting every corner of the U.S. "I've now been in fifty - seven states? I think one left to go. Alaska and Hawaii, I was not allowed to go, even though I really wanted to visit but my staff would not justify it." News accounts at the time chalked it up to fatigue during an exhausting stretch of campaign travel.
Perry hoped to stem any fallout from his own gaffe through a blitz of early morning interviews and TV appearances. He added an appearance on the "Late Show with David Letterman" for Thursday evening.
His glaring mistake was by far the worst in a series he's made over the course of six presidential debates. The pattern plays into stereotypes that the Texas governor isn't smart enough or qualified enough to be president - particularly as Mitt Romney, the Republican candidate to beat, has stood on the same stages and performed almost flawlessly.
It also raised questions about whether Perry can take on not just his Republican rivals but also Obama.
In the early morning after the debate, Perry tried to cast the mistake as a humanizing one that shows voters he isn't the "slickest" politician but someone who makes mistakes like everyone else. In the AP interview, he insisted that he is more qualified than Romney to be president.
"More so," he said when asked if was as qualified as the former Massachusetts governor. "Almost 11 years of chief executive experience of an entity a lot bigger than anything that he ever ran, and created more jobs, taking our four years and overlapping them as governors. The success that Texas was going through between 2002 and 2006 far overshadowed Massachusetts. So absolutely."
"If Americans are looking for the slickest politician, the smoothest debater, I readily admit, I'm probably not their guy," Perry said.
But while Perry's earlier flubs brought him down from the top of the polls and forced a shift in campaign strategy, this one has prompted questions about whether he can even continue in the race. Donors were privately nervous - or even panicking, though Perry's advisers said Thursday that they already have the cash they need to run through to South Carolina.
And Perry himself is defiant. "The chattering class and the political pundits will try to guide this campaign," Perry said. "I'm going to be out talking to the people in South Carolina and Florida and New Hampshire and Iowa, those early primary states, about our vision for the country."
Still, the extended debate exchange is destined for endless television replay and will provide easy fodder for attack ads.
In the debate, Perry said he would eliminate three federal agencies but struggled to name them.
"Commerce, Education and the - what's the third one there? Let's see," he said.
Perry's rivals tried to bail him out, suggesting the Environmental Protection Agency.
"EPA, there you go," Perry said, seemingly taking their word for it.
But that wasn't it. And when pressed, he drew another blank.
"Seriously?" asked moderator John Harwood, one of the CNBC debate hosts. "You can't name the third one?"
"The third agency of government I would do away with - the Education, the Commerce. And let's see. I can't. The third one, I can't," Perry said. "Oops."
Later in the debate, Perry revisited the question and said he meant to call for the elimination of the Energy Department.
On Thursday, Perry said he just couldn't think of it.
"There were so many federal agencies that come to mind, that I want to get rid of, that the Energy Department would not come out," he said in an interview taped for ABC's "Good Morning America."
He's trying to turn it to his advantage. On NBC's "Today" show, Perry sought to make the best of the gaffe, saying that forgetting the name of one of the agencies illustrated the "core point" of his campaign - that there are too many agencies. He's already blasted an email to supporters asking them, "What part of the Federal Government would you like to forget about the most?" His website now asks them to vote for one.
The immediate fallout has been brutal.
"We all felt very bad for him," Michele Bachmann, the Minnesota congresswoman also running for the nomination, said after the debate.
"Rick Perry just lost the debate. And the entire election. You only had to name three," Tim Albrecht, the top spokesman for Iowa Gov. Terry Branstad, who is unaligned in the GOP race, tweeted from his personal account.
"Perry response will be on highlight reels for years to come," tweeted businessman Jack Welch.
His campaign obviously recognized just how bad it was. In dramatic fashion, Perry bee-lined it to the "spin room," the place where reporters gather to interview campaign surrogates, and immediately indicated that he knew he had made a really bad mistake. The first words out of his mouth as reporters crowded around were: "I'm glad I had my boots on because I really stepped in it tonight."
The next few days will shed light on whether voters care about the misstep - and punish him for it.
Over the past two weeks, Perry has sought to prove he's still a credible challenger to Romney by rolling out detailed policy proposals. But he's found himself dogged by suggestions that he had been drinking or taking drugs when he gave an animated speech in New Hampshire. It went viral online, prompting Perry to state that he was not, in fact, under the influence of a substance.
NBC's "Saturday Night Live" did a widely viewed Perry parody last weekend.
In recent days, the candidate started to take his message directly to voters by running sunny, biographical television ads in early primary states like Iowa and New Hampshire. It's an effort to reintroduce himself to Republican primary voters in a safer setting that circumvents the news media.
Wednesday's was the latest tough debate for the GOP candidate who has struggled in the national spotlight since entering the race in August, the last time he was at the top of polls. His standing has fallen throughout the fall, and he's fighting to gain ground less than two months before the leadoff Iowa caucuses.
He has committed to four more debates in a year when the GOP electorate is clearly tuned into them, but his advisers are considering skipping future ones.
Presidential debates have offered pivotal moments for decades, from Al Gore's audible sighs in 2000 to Michael Dukakis' tepid answer about the death penalty in 1988.
A statement by Gerald Ford in a 1976 presidential debate is among the most memorable, however. Ford famously baffled audiences when he said, "There is no Soviet domination of Eastern Europe" and refused to back down when pressed by the moderator. The moment haunted the rest of his losing campaign.
Perry canceled private fundraisers in Tennessee and instead headed to New York for another round of interviews, including the appearance with Letterman. His next public campaign stops were scheduled in South Carolina on Friday - the day before yet another debate.