When the Romney sons were asked in New Hampshire today whether their father would release his tax returns, Matt Romney said he didn't know the answer, but went on to add that he'd heard someone suggest that dad might do so as soon as Obama releases his college grades and birth certificate.

Tagg Romney, 41, the oldest Romney son, quickly jumped in, saying, "That was not my dad saying that."

For added clarity, Matt Romney, 40, later tweeted, "I repeated a dumb joke. My bad."

Video of the moment was posted by the Concord Patch site HERE.

President Obama's birth certificate has been the subject of conspiracy theories for years and most recently by real estate mogul Donald Trump. Obama released a copy of his "certificate of live birth" during his presidential campaign in an attempt to quell the rumors that he was not born in America.

The White House released copies of his original birth certificate in April.

Then-Sen. Barack Obama of Illinois also released his tax returns during the Democratic presidential primary race in March 2008, but has not put out his college transcripts.

ABC News' Emily Friedman contributed to this report.