Donald Trump is determined to have "birtherism" front and center in the 2012 presidential election, calling it the "most important thing" just hours before he was set to attend a fundraiser for the presumptive GOP nominee, Mitt Romney.

On Tuesday morning, Trump appeared via telephone on CNBC, where he argued that questions about Obama's birthplace have not been adequately answered, despite Obama releasing a copy of his birth certificate over a year ago.

"Nothing has changed my mind," he said.

Trump was skeptical about a recently unearthed promotional booklet from Obama's former literary agency that erroneously reported the president was born in Kenya. After the discovery of the booklet reignited rumors that Obama is not a natural-born American citizen, the author of his biography quickly came forward and said the mistake was a simple fact-checking error.

Trump, however, was not convinced. "Look, a publisher come out last week and had a statement about Obama given to them by Obama when he was doing a book as a young man, a number of years ago, in the 90s," he said. "Now amazingly, the publisher is 'oh we made a mistake.'"

"[Obama was] a young man doing a book, and he said what he believed to be the truth."

Unsatisfied with Obama's birth certificate, the authenticity of which he said many people have "serious doubts" about, he called for Obama to provide his academic transcripts from Columbia, Harvard and Occidental College.

"A lot of people want to see his college transcripts," Trump said. "They're not looking at his marks, his grades. ... They want to see, what does he say about place of birth. Now, those transcripts have disappeared, nobody seems to be able to get them."

While Romney has said he does not share Trump's views, he has declined to repudiate them. On Monday, Romney told reporters he doesn't agree with all the people who support him, but he was "appreciative to have the help of a lot of good people."

The Obama campaign, sensing an opportunity to taint Romney with Trump's provocative statements, released a web video Tuesday contrasting Romney with Sen. John McCain (R-Ariz.), who famously denounced supporters who questioned Obama's citizenship.

Trump indirectly addressed the Obama ad on Twitter, urging Romney not to dismiss the birther movement -- or risk losing the election.

.@BarackObama is practically begging @MittRomney to disavow the place of birth movement, he is afraid of it and (cont) http://t.co/eHvjlV0S — Donald J. Trump (@realDonaldTrump) May 29, 2012