Donald Trump today pledged $5 million to a charity of President Obama's choice, provided the president makes public his college applications and transcripts and releases his passport history, a far cry from the October-surprise bombshell Trump had promised.

Calling the offer a "major announcement," Trump released a video via Twitter at noon to much ballyhoo, and his online followers grew by the hundreds in the moments before the video was released.

"I have a deal for the president," Trump said. "If Barack Obama opens up and gives his college records and applications, and passport application and records, I will give to a charity of his choice, a check immediately for $5 million."

Trump, the New York billionaire real estate developer whose knack for self-promotion and showmanship have landed him a reality-television show, has needled the president in the past, calling him the "the worst president ever" and briefly threatening to run against him.

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Trump took credit last year when Obama was forced to release his birth certificate, laying to rest a long-simmering rumor that the president was not born in the United States.

"I'm very honored to have got him to release his long-form birth certificate, or whatever it may be," Trump said in the video.

Since the release of the birth certificate in April 2011, Trump has called on the president to release other personal documents, including his college transcripts.

"President Obama is the least transparent president in the history of this country," Trump said. "We know very little about this president."

A frequently disproven conspiracy theory has dogged Obama since his 2008 election, that he has not been forthcoming about his past in an effort to cover up shady details about his biography, including his place of birth.

See how Twitter users reacted to Trump's announcement HERE

Obama has written two memoirs that delve into his African heritage and childhood spent partly in Indonesia.

When asked about Trump's comments, Obama campaign chief David Plouffe told reporters: "Direct your questions to Boston [Mitt Romney's campaign headquarters], he's Romney's biggest supporter."

Trump had been teeing up this announcement for days, and many hoped for a game-changing October surprise.

Separately, liberals were also hoping for a late-breaking smear on Mitt Romney that would alter a neck-and-neck race for the White House, but that also fell flat today.

A Massachusetts judge will hold another hearing Thursday before deciding whether to unseal testimony Romney gave in a 1990s divorce case. Some people have accused Romney of lying under oath so a friend and political backer, Staples founder Tom Stemberg, would not have to pay a settlement his wife.

Calls to Romney's attorney were not immediately returned.