Donald Trump has revealed that he is prepared to offer U.S President Barack Obama even more money to reveal his education and passport records.The Celebrity Apprentice host sent a public message to the US president earlier this week, stating that he would donate $5 million (£3.1 million) to a charity of Obama's choice if the politician brought forth his passport documents and college transcripts.Obama appeared on Jay Leno's Tonight Show on Thursday evening, making fun of Trump's offer.Business mogul Trump has insisted that the offer is not a publicity stunt, and in an upcoming appearance on David Letterman's late night show, said he has no strings attached.He said: "I assume and I hope that his records are perfect. He picks up $5 million for charity. $5 million. From me. Immediate. Check written. I'd even go more to be honest. There, you have a scoop."When asked why he wanted the records released, the businessman answered: "Transparency. Does that make sense to anybody?"Trump has challenged President Obama in the past, calling for the release of the politician's birth certificate to prove his US citizenship. BBC