ROCHESTER, Mich. — Republican presidential hopeful Rick Perry says he would eliminate three federal agencies. Just don’t ask him to name them.

“Commerce, Education and the — what’s the third one there? Let’s see,” the Texas governor said during a debate Wednesday night.

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, the candidate drew another blank.

“Seriously?” moderator John Harwood, one of CNBC’s debate hosts, asked. “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.

After the debate, Perry bee-lined it to the crush of reporters gathering to interview campaign surrogates — and he immediately indicated that he knew he had made a really bad mistake. The first words out of his mouth as reporters crowded around: “I’m glad I had my boots on because I really stepped in it tonight,” he said.

Perry added: “People understand that it is our conservative principles that matter.”

“We all felt very bad for him,” Michele Bachmann, the Minnesota congresswoman also running for the nomination, said after the debate.

The next few days will shed light on whether voters care about the misstep — and punish him for it.