Trump with CNN host Anderson Cooper. CNN Real-estate developer Donald Trump says he no longer has any interest in so-called birther theories.

But he's not backing down, either.

In a Thursday interview on CNN, the provocative GOP presidential candidate said he wouldn't admit he was wrong about questioning President Barack Obama's birthplace years ago.

"I don't know. I really don't know," Trump told anchor Anderson Cooper when asked whether he accepted that Obama was born in the US.

The Republican businessman was one of the most prominent people to cast doubt on Obama's birthplace before the president ultimately released his long-form birth certificate in 2011, which showed he was born in Hawaii. Before then, Obama was long dogged by conspiracy theorists who maintained he was actually born in Kenya and, according to them, ineligible to be president.

"He came up with this thing, all of a sudden, miraculously," Trump said of Obama on Thursday.

Trump stressed that his presidential platform was focused on jobs and the military but that he would say "one thing" about the birther controversy: Obama's various opponents in the 2008 presidential race were also trying to find his birth certificate.

"Do you know that Hillary Clinton was a 'birther'? She wanted those records and fought like hell," he said. "People forgot. Do you know that John McCain was a 'birther'? They couldn't get the records. Hillary failed. John McCain failed. Trump was able to get [Obama] to give something. I don't know what the hell it was.

"But it doesn't matter because I'm off that subject," he added. "I'm about jobs. I'm about the military. I'm about doing the right thing for this country. I want to make our country great again."