Romney goes THERE: 'Birther' joke raises conspiracy theory

Commerce, Michigan (CNN) - Mitt Romney denied in an interview Friday that his reference to a highly charged political symbol - a birth certificate – was anything more than simply of homecoming humor.

"No, no, not a swipe," Romney said in the CBS interview referring to President Obama and the conspiracy theories over whether he was born in the United States. "I've said throughout the campaign that and before, there's no question about where he was born."

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"He was born in the U.S. This was fun about us and coming home, and humor - you know, we've got to have a little humor in the campaign as well," Romney continued.

Of course, humor needs a punch-line or it's not a joke.

It was a Friday campaign rally in Michigan, the state where Romney was born, where he chose to say, "Ann was born at Henry Ford hospital, I was born at Harper hospital. No one has ever asked to see my birth certificate. They know that this is the place that we were born and raised."

A fringe of conservative Republicans continue to believe that President Barack Obama was not born in the United States. Those in that movement are referred to as "birthers."

A certification of live birth released by Obama during the 2008 campaign, and then the long-form certificate released by the White House in the spring of 2011, both stated the president was born in a Hawaii hospital on August 4, 1961. Contemporaneously published newspaper announcements also noted the birth in the Aloha State. Only "natural born" citizens of the United States are eligible to be president.

Romney said in the interview that the comment was some much-needed humor in this fiery campaign.

"Well we're in Michigan and Ann and I were both born in Detroit, and of course a little humor always goes a long way," Romney said. "So it was great to be home, to be in a place where Ann and I had grown up and the crowd loved it and got a good laugh."

But Obama's campaign was not laughing.

"Throughout this campaign, Governor Romney has embraced the most strident voices in his party instead of standing up to them," spokesman Ben LaBolt said in a statement after the campaign stop, but before the interview.

"It's one thing to give the stage in Tampa to Donald Trump, Sheriff Arpaio, and Kris Kobach. But Governor Romney's decision to directly enlist himself in the birther movement should give pause to any rational voter across America."

LaBolt's statement referenced some of the highest-profile figures who continue to perpetuate the "birther" line, including Donald Trump, who earlier this year endorsed Romney and has said he will have a high-profile role at the Republican National Convention next week. Trump increased the drumbeat for the White House to release Obama's long-form in the spring of 2011, just prior to its release. Despite the document being in the public sphere, Trump has continued to question Obama's birthplace in media appearances and in social media posts.

Romney senior adviser Kevin Madden said after the candidate's remarks, "The governor has always said, and has repeatedly said, he believes the president was born here in the United States. He was only referencing that Michigan, where he is campaigning today, is the state where he himself was born and raised."

Another aide noted that Romney "wasn't using prepared remarks."

In his Friday remarks, Romney's reference was to his own birth certificate, not that of Obama. Nevertheless, the crowd roared when Romney made the quip, and many supporters afterwards said they remained skeptical about where Obama was born.

"I thought it was great because why should we have to worry about whether the president has a birth certificate or not," Guy Myers of Clarkston, Michigan, said.

Another supporter, Lauri Pierce of Midland, said it drew a contrast for her between Romney and Obama.

"Well Mitt's from Michigan. There's no question about where he's from," Pierce said. "And you hear a lot of questions about Obama. You don't know, but you hear questions."

CNN's Rachel Streitfeld, Jim Acosta and Gregory Wallace contributed to this report.