Meanwhile, Donald Trump hosted a fundraiser for Romney in Las Vegas.
Romney has made it very clear he's convinced President Obama was born in the U.S.
But Trump is sticking to his guns -- quite vocally -- about his doubts.
During a testy exchange Tuesday night, Donald Trump maintained to CNN's Wolf Blitzer that Barack Obama's state of Hawaii birth certificate and newspaper birth announcements prove nothing.
(Trump) "A lot of people do not think it was an authentic certificate." (Blitzer) "How can you say that?" (Trump) "You won't report it, but many people do not think it was authentic. His mother was not in the hospital, there are many other things that came out."
(Trump) "Many people put those announcements in because they wanted to get the benefits of being so-called born in this country."
Newt Gingrich also took part in Tuesday's fundraiser for Mitt Romney, and weighed in.
"Far be it for me to suggest to the Donald what he should do. Governor Romney is not distracted, the Republican party is not distracted. We believe that this is an American-born, job-killing president."
Romney explained how he reconciles Trump's position on Monday.
"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. But I need to get 50.1% or more and I'm appreciative to have the help of a lot of good people."
The white house says it was forced to address the issue last year to end what it called..."a ridiculous distraction."
"We can revisit that but I think the American people are pretty fed up with this kind of nonsense," said Jay Carney, White House Press Secretary.
Obama's campaign released a web video on Tuesday that said the 2008 GOP nominee John McCain stood up to the voices of extremism in his party.
It then asked why Mitt Romney won't do the same.
In the video, McCain is seen addressing a woman who called Obama an "Arab."
McCain says Obama is a decent family man and citizen that he just happens to have disagreements with.
(Ed Payne for CNN)