White House adviser David Plouffe doubled down Friday on Democrats' call for Mitt Romney to release more of his tax returns.

"If he's got nothing to hide, then there's nothing to lose," Plouffe said in an interview with Bloomberg TV set to air Friday night. "I think it's a simple question of they're sitting there, they've all [been] prepared. I'm sure a lot of accountants spent a lot of time on these tax returns. Just release them.

"And what's important is, listen, the American people want to have trust in their leaders."

The White House released the tax returns for President Obama and Vice President Biden on Friday, and, in turn, called for Romney to release more of his tax returns. The former Massachusetts governor has already released tax returns for 2010 and and an estimate of his 2011 tax returns.

In response to Plouffe's comments the Romney campaign said the White House was just trying to distract from focusing on other issues, like the economy.

"Gov. Romney has already released his 2010 return and an estimate of his 2011 income and taxes. He will release his full 2011 return when it is filed," Romney spokesperson Amanda Hennenberg said in a statement.

Romney's tax returns for those years showed that he paid $6.2 million in taxes on an income of $42.5 million. Most of Romney's income for those years came from investments, and he paid a tax rate of 13.9 percent. 

The Obama administration wants to raise the tax rate for the wealthiest Americans through the "Buffett Rule," which would ensure that the wealthy pay a higher tax rate than the middle class.

A poll released by Gallup on Friday found that 60 percent of Americans favored passing the Buffett Rule, while 30 percent opposed it. Broken down by party affiliation, 43 percent of Republicans favored passing the legislation and 54 percent opposed. For Democrats, the poll found that 74 percent supported the legislation's passage while 24 percent opposed it.

—This story was updated at 5:00 p.m.

Obama's tax returns showed that he and the first lady paid $162,074 in taxes on an income of $789,674, meaning his family paid an effective tax rate of 20.5 percent. Vice President Biden and his wife paid $105,357 on $379,035 in taxes, for an effective rate of 27.8 percent.