(CNN) - Donald Trump did not back down Tuesday from his questioning of President Barack Obama's birthplace, instead arguing heatedly with CNN's Wolf Blitzer that "a lot of people do not think it was an authentic certificate," though he declined to offer names of experts who agree with him.
The issue of Obama's birth - litigated in the 2008 presidential campaign, then settled when the Obama White House released the longform version of the certificate in April 2011 - is being brought to the fore in no small part by Trump, who is also set to fundraise alongside presumptive Republican presidential nominee Mitt Romney Tuesday evening.
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On CNN's "The Situation Room" Tuesday, Trump maintained that Obama's birthplace is a matter of opinion, rather than fact.
"Everybody's entitled to your opinion," he said. "You know my opinion and you know his opinion and that's fine. We're entitled - as he said yesterday in the airplane - we're all entitled to our opinions and he's entitled to have his opinion. I don't happen to share that opinion, it's wonderful."
Blitzer presented Trump with newspaper announcements of Obama's birth from 1961.
Trump interrupted, "Can you stop defending Obama?"
"Donald, you're beginning to sound a little ridiculous, I have to tell you," Blitzer replied.
"You are, Wolf," Trump fired back. "Let me tell you something, I think you sound ridiculous."
Trump then alleged that the practice of filing U.S. birth announcements for an overseas birth was commonplace, though he offered no evidence.
"Many people put those announcements in because they wanted to get the benefits of being so-called born in this country," Trump said. "Many people did it."
Obama's longform birth certificate showed he was born in Hawaii on August 4, 1961 and was acknowledged as authentic by state officials. Natural born American citizenship is one of the Constitutional requirements for the presidency.
"Is it the most important thing?" Trump asked in an interview earlier on Tuesday. "In a way it is. You're not allowed to be the president if you're not born in the country."
Trump finds himself at odds with GOP presidential candidate Mitt Romney, whose spokeswoman pointed out in an email statement that "Governor Romney has said repeatedly that he believes President Obama was born in the United States."
But Romney made no effort to distance himself from the comments, even when presented with the opportunity by reporters on Monday.
"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 when asked about the issue. "But I need to get 50.1% or more and I'm appreciative to have the help of a lot of good people."
Trump said he has not spoken about the birther issue with Romney
"I haven't talked to Mitt Romney about it," he said. "What I speak to Mitt Romney about is jobs. What I speak to Mitt Romney about is China, because he's got a great view on China and how they're taking our jobs and taking our product and manipulating their currency so it makes it almost impossible for our companies to compete."
Trump spoke by phone with Blitzer in the interview from Las Vegas, where he and Romney will fundraise with former GOP presidential candidate Newt Gingrich.
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… Why won't Mitt Romney do the same?" In the video, McCain is seen addressing a woman who called Obama an "Arab," saying, "He's a decent family man, citizen that I just happen to have disagreements with."
The president's deputy campaign manager suggested Romney's alliance with Trump in light of the tycoon's statements calls into question how he would serve as president.
"Mitt Romney's continued embrace of Donald Trump and refusal to condemn his disgraceful conspiracy theories demonstrates his complete lack of moral leadership," Stephanie Cutter said in a Tuesday afternoon statement. "If Mitt Romney lacks the backbone to stand up to a charlatan like Donald Trump because he's so concerned about lining his campaign's pockets, what does that say about the kind of President he would be?"
White House Press Secretary Jay Carney said Tuesday the White House was forced to address the issue last year, "but not because we chose to, but because it was such a ridiculous distraction from the important business that we should be doing here that the president is committed to doing and Congress should be doing to help the economy grow and help it create jobs."
"We can revisit that but I think the American people are pretty fed up with this kind of nonsense," he said.
As evidence of his claims, Trump pointed to a biographical note published in the 1990s by Obama's literary agent, which said Obama was born in Kenya.
The literary agent recently apologized for the mistake.
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Romney is a SELL OUT. Why else would he associate himself with a carnival barker? Romney has no spine.
I'm so glad we have Donald Trump. He's the only fun we have left in this tedious, obnoxious political season.
After all, Trump's status as a child of privilege and rampant narcissism could only be possible because he inherited a mere 50,000 apartments in NYC. Would that we all should be so lucky! Talk about making the least of things.
That said, I really think Mitt Romney could not have picked a more toxic friend. But, maybe that's a signal of who he is. It's about time we knew more about that.
He was listed as being born in Kenya by his literary agent for over a decade. That is not a typo.
Where is Marco Rubio's birth certificate?
I wonder how the Donald's investigation into the birther issue is going. NOT good I'm guessing, or we'd have had Tramp all over the MSM with the "news"..
I Think Kathy has said it all......go away to one of the other countries that you have your money at!
The hospital, not the parents, put the birth announcement in the two newsletters. That was the standard. I wish the media would stop giving air time to Trump; he's such a dope.
I can't help but laugh as I think Donald Trump is the most arrogant, self-absorbed man. Really, it is comical to listen to him. He really does this for his own ratings and the way he puts others down is just ridiculous. I think he just needs a full sized makeup compact so he can look at himself all day long to boost his EGO!!! I agree, with Kathy, who is he and and just stop putting him on the news and hopefully he will just go back to Celebrity Apprentice with it own "slumping" ratings!
Romney has been trumped and should drop out of the game.You can't really tell who is running and who is just the surrogate. Seems to me that when Trump is around ,Romney is a just a poor number 2. How sad it that?,
What's wrong with u trump? Brain damage? Yes!he (obama will be your next president again...)How will u like that?
Trump never changes. He is still the ultimate bad taste, bad upbringing, ugly and overweight and the his tasteless
sales-manager, shiny pink ties.
My SIL is a "birther" judging by her comments about Obama. There is no reasoning with these people and racism is at its core.
Trump needs a biology lesson. Women give birth to babies, not men. Obama's mother was a US citizen and never went to Kenya.
If trump wants to be believed on this birther issue he needs to stick to interviews on fox news
Give Trump a NFL team...
Wolf is right – Donald Trump is ridiculous! He is an absolute joke and anyone who believes anything he says is a total fool.
Opinion?? Opinion?? It's not a matter of opinion, it's a matter of a fact that has been proven and re-proven by now. THAT's what makes The Donald sound ridiculous.
Trump is lying to get ratings for his televison show.
If anyone knows fake, it's Donald Trump. He's been one all his life. As a politician, he would make a better garbage man because that's all that comes out of this loser's mouth. Have some backbone, Romney. Tell the world this man is not part of your entourage...or is political cash more important than character?
Miriam Goderich, now in successful publishing executive has explained the phamplet error numerous times. Miriam states that in 1991, she was an assistant at Obama's publisher. By error, she wrote that Obama had been born in Kenya. Trump knows all of this but continues to attribute his position that Obama was born in Kenya to the phamplet.
We just need to acknowledge that Trump is a fool and let it go at that.
This man is nuts and really stupid, pure and simple.
Has Trump seen Romney's birth certificate (which, for some strange reason, he's rejected countless requests to release for years)? And why on earth don't reporters simply ask Trump for that report of his "investigation" of Obama's birth certificate that he promised would show the world that he's illegitimately in office? I can't understand why Trump isn't met with that question everywhere he goes. Or why Romney would want to use him as a spokesperson for his campaign. I've had my doubts about Romney. His spineless embrace of Trump just confirms my worst fears about him.
I can never look at Don without focusing on that wispy pomp-a-doo. I'm transfixed on his coiffure. But I will give him credit. His game plan it to stick to Romney and milk him for about a billion dollars in free publicity. Win, lose or draw for Mitt, Don will win the free "PR."
Every member ot the teaparty should have a reality check–look in the mirror, this is waht you look like. Trump without the money. He is playing you so he can lower his taxes.
Wow, this is about as close to decent journalism as Blitzer has done in ages. About time. Maybe other so-called journalists will do this more often.