Speaking to Univision on Sunday in an interview at the Summit of the Americas in Colombia, Obama said candidates for president should be “as transparent as possible.”

"I think that it's important for any candidate in public office to be as transparent as possible, to let people know who we are, what we stand for,” Obama said. “And you know, I think that this is just carrying on a tradition that has existed throughout the modern presidency.”

Romney has released his 2010 returns and an estimate for 2011, which show he paid an effective tax rate of about 14 percent.

On Friday, shortly after the White House released tax returns from Obama and Vice President Biden, Romney filed for an extension, which his campaign said is routine.

Also on Friday, White House adviser David Plouffe urged Romney to release his 2011 returns immediately, to show that “he’s got nothing to hide.”

Republican National Committee Chairman Reince Priebus pushed back on Sunday in an interview with CNN, accusing Obama of using “shiny objects,” such as Romney’s tax returns, to distract voters from his record.

“Again what we’re talking about is the tactic of this president to talk about tax returns and a Buffett Rule when in reality we have bigger issues to talk about,” Priebus said. “This election won’t come down to a tax return, this election will come down to the state of the economy and how Barack ObamaBarack Hussein ObamaPatagonia files suit against Trump cuts to Utah monuments Former Dem Tenn. gov to launch Senate bid: report Eighth Franken accuser comes forward as Dems call for resignation MORE failed this country.”