Donald Trump. AP Photo/Jim Cole Real-estate magnate Donald Trump brushed off questions on Wednesday about whether President Barack Obama is a natural-born citizen.

"Who knows? Who cares right now? We're talking about something else, OK?" Trump said during a CNN interview.

The Republican presidential front-runner continued: "I mean, I have my own theory on Obama. Someday I'll write a book. I'll do another book. It'll do very successfully. "

He said that after CNN anchor Wolf Blitzer said that some people saw a connection between Trump's questioning of Obama's birth certificate and his recent declaration that voters should be concerned about Sen. Ted Cruz's (R-Texas) Canadian birthplace.

Trump, when asked, has repeatedly suggested that Cruz could get tripped up by the constitutional requirement that presidents are "natural-born" citizens.

Legal experts believe that Cruz wouldn't have any problem meeting this threshold because, like Obama, Cruz's mother was an American when he was born.

But Trump told Blitzer that a potential legal challenge to Cruz's eligibility could be a looming threat for the senator if he became the Republican nominee. Trump urged Cruz to get a "declaratory judgment" from the court system in order to settle the issue.

"I think I'm going to win. I'm leading in every poll by a lot. But ... if Ted should eke it out — and I hope that doesn't happen — and he's got this cloud over this head, I don't think that it's going to be possible for him to do very well. I don't think it's actually possible for the Republicans to let it happen. Because he's got this cloud," Trump said.

Trump also blamed reporters for bringing up the issue of Cruz' birthplace.

"There's this doubt. People have doubt. Again, this was not my suggestion. I did not bring this up. A reporter asked me the question," Trump said, an apparent reference to a Washington Post interview earlier this week.

"That's a tough matter for Ted," the businessman added. "Again, I didn't bring it up, Wolf. This is brought up and this was asked to me as a question. It's not the first time it's been asked, but it's being asked by a lot of different people."

Trump was once one of the most prominent people questioning the authenticity of Obama's US birth certificate. But during his 2016 campaign, Trump has done his best to avoid discussing the issue.

"You know the problem talking about that question?" he told MSNBC's Chris Matthews in December. "Here's the story. I don't answer because you know what? If I do answer, that's all people want to talk about."