Donald Trump says he'll disclose his finances if he runs for president, but may not release his income tax returns unless President Obama releases his birth certificate.

Trump made his comments in a wide-ranging interview with ABC's Good Morning America. He has vowed to say by June whether he'll seek the Republican presidential nomination in 2012.

The real estate executive told host George Stephanopoulos that he's "done a great job" with his company and vowed to "do a full disclosure of finances."

But when asked if he'd release his tax returns -- as Obama did yesterday and as presidential candidates have done in the past -- Trump balked and brought up the issue of Obama's birth certificate.

"We'll look at that," Trump said. "... I'd love to give my tax returns. I may tie my tax returns into Obama's birth certificate."

Trump has made Obama's birthplace and birth certificate an issue. The president was born in Hawaii and his birth certificate has been certified by Hawaii's health director as real. But the issue has repeatedly come up since Obama first ran for president in 2008, fueled in part by people in the blogosphere known as "birthers."

Trump has been dismissed by Republicans such as House Majority Leader Eric Cantor and Bush political strategist Karl Rove for questioning the legitimacy of Obama's birth certificate. Polls by CNN, ABC and The Washington Post show Trump rising near the top of the unsettled GOP presidential field.

Obama told ABC recently that he doesn't believe the American people are "really worrying about conspiracy theories ... or birth certificates," adding this kind of stuff "presents a problem" for people like Trump.

In the interview, Trump also discussed why he no longer supports abortion rights, saying he changed his mind "quite a while ago." Asked if he was concerned about getting criticized for flip-flopping on issues, Trump said "I'm sure I will."