WATCH:

COMMERCE, Mich. - At a rally meant to highlight Mitt Romney's hometown roots here in Michigan, a joke delivered by the candidate seemed to make reference to the fringe birther controversy that suggests President Obama was not born in the United States.

"Now, I love being home in this place where Ann and I were raised, where both of us were born," said Romney. "Ann was born in Henry Ford Hospital. I was born in Harper Hospital."

"No one's ever asked to see my birth certificate," said Romney. "They know that this is the place that we were born and raised."

Romney advisor Kevin Madden said in a statement Romney was merely referring to his upbringing here, not the questions that have been raised about the president's birthplace. Both Obama and Romney have released their birth certificates.

In an interview with CBS News later in the day, Romney said the remark was not meant as a swipe to the president.

"No, no, not a swipe," Romney told CBS News' Scott Pelley. "I've said throughout the campaign and before, there's no question about where he was born. 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 a campaign."

But Obama's campaign spokesman Ben LaBolt thinks otherwise, writing in a statement, "Governor Romney has embraced the most strident voices in his party instead of standing up to them. 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."

In May, the state of Hawaii said it has provided verification of the president's birth to Arizona's secretary of state, who claimed he needed proof of Obama's citizenship before he could place his name on the state's November ballot.

Romney surrogate and media mogul Donald Trump has been the main proponent of the birther theory, earlier this May pointing to old promotional material for Obama's publisher that listed the president as being born in Kenya. "A book publisher came out three days ago and said that in his written synopsis of his book, he said he was born in Kenya and raised in Indonesia. His mother never spent a day in the hospital," Trump told the Daily Beast's Lloyd Grove at the time.

Miriam Goderich, who was a bio editor at Obama's former literary agency admitted in a statement to Yahoo News that it was a fact checking error which misidentified Obama's birthplace as Kenya while trying to promote the then-Harvard Law grad as an author in 1991.

Romney, who was set to raise money with Trump that same week, told reporters at the time that he doesn't agree with everyone who supports him.

"You know I don't agree with all the people who support me, and my guess is they don't all agree with everything I believe in," Romney said in May. "But I need to get 50.1 percent or more and I'm appreciative to have the help of a lot of good people."

The rally was supposed to be a homecoming for the Romneys - and an opportunity to introduce Ryan to voters in the state where Romney's father was governor.

"I love coming to a place where I put up my hand and everybody knows what that means! Mitt and I grew up here, we fell in love here, and this is a special place for us, and we want to have a big W next to Michigan in November," said Ann Romney, growing emotional. "I have to say, when I got on the stage I didn't appreciate how many people were here until I stood up here, and I got quite choked up, because it's amazing!"

"It's amazing that people in Michigan have not forgotten the promise of America and the promise, the promise of Mitt's father and my father who made their livings here, and who came here. Both of our fathers came here and made their livelihoods here," she said.