Former House Speaker Newt Gingrich on Thursday was questioned whether President Barack Obama was a United States citizen at campaign event in Storm Lake, Iowa.

Many of the so-called “birthers” believe there is persuasive evidence that Obama was born in Kenya in 1961 and that his birth certificate was faked in order to make him eligible for the presidency.

"According to the Constitution, those who are running for office must be a citizen of the United States," a woman asked him. "Now, you know where I am going with this. So, before you have your debate, why does Mr. Obama not have to exactly prove his citizenship as he is going to all these other countries. In Arizona, if I have my facts correct, they are refusing to put his name on the ballot because he has not proven that he is a citizen. Is that true?"

"No," Gingrich responded. "Let me answer this... All I can report is the state of Hawaii has certified that he was born there. [Callista and I] were with a taxi driver one day who showed us the hospital. There is every reason to believe he is a citizen of the United States. The fact is he is already a terrible president. We don't have to go beyond that."

"This is one of those issues where it is a fact. He is the President of the United States. Therefore, at a factual level, the citizenship is a moot issue. He is the president. And he is not going to lose the presidency over that. He'll lose the presidency because all of us are going to vote him out."

Legislation that would have required presidential candidates to prove they are natural born American citizens before their names can appear on the Arizona ballot was vetoed by the state’s Republican governor, Jan Brewer, in mid April.

In an attempt to quiet the "birther" conspiracies, Obama released his long-form birth certificate in late April. It confirmed what his other birth certificate released in 2008 said: the president was born in Honolulu, Hawaii on August 4, 1961.

Watch this video from CNN, uploaded Dec. 29, 2011.