Donald Trump has challenged President Obama to release his college and passport records in return for a $5m donation to charity.
The real estate mogul made the announcement in a video posted on his Twitter account . He called MrObama "the least transparent president in the history of this country".
The billionaire businessman, who has endorsed Republican Mitt Romney in the presidential race, had been whipping up anticipation by announcing his intention to reveal "an October surprise" that could change the race for the White House.
In his video, he said: "I have a deal for the president. A deal that I don't think he can refuse, and I hope he doesn't."
But Sky's Amanda Walker, speaking from Washington, said the reaction in the President's camp had been muted.
"I don't think anyone was taking it too seriously," she said.
"In Obama's campaign team it's not really causing shockwaves, they've got bigger things to think about".
Obama campaign chief David Plouffe simply told journalists: "Direct your questions to Boston (Romney HQ), he's Romney's biggest supporter".
Mr Trump was one of the leading exponents of the so-called "birther conspiracy", which held that Mr Obama had been born in Kenya, making him ineligible to hold the US presidency.
The theory was eventually laid to rest in 2011 after the White House released the long form of the president's birth certificate, showing his birthplace as Hawaii.
The president went on to use his speech at the White House Correspondent's Dinner in April 2011 to take jabs at Trump.
He said: "Now, I know that he's taken some flak lately, but no one is happier, no one is prouder to put this birth certificate matter to rest than the Donald.
"And that's because he can finally get back to focusing on the issues that matter. Like, did we fake the moon landing? What really happened in Roswell? And where are Biggie and Tupac?"
Ahead of Mr Trump's announcement Douglas Kass, who appears on the same business talk show as the tycoon, suggested it would revolve around the previously-aired rumour that the Obamas were seriously considering getting divorced in 2000.
The White House quickly denied that story when it first appeared last June in a controversial biography by author Ed Klein.
Mr Trump has previously considered running for president himself, but he chose to endorse Republican candidate Mitt Romney earlier this year.
