Fifty-six percent of Americans think Mitt Romney should release his tax returns from the last 12 years while 34 percent think he should not, according to a new poll from Public Policy Polling. Among Independent voters, 61 percent want Romney to release his returns, while just 27 percent say he shouldn't.

The left-leaning Public Policy Polling is the first to measure whether voters think Romney should release his tax returns, and it finds that, overwhelmingly, people are curious.

PPP's 12 years of returns as a benchmark is significant for two reasons — because Obama has released 12 years of returns and because Romney's father, George, disclosed 12 years during his 1968 White House bid.

Along similar lines, 56 percent of voters — 58 percent of Independents — think Romney should release financial records that document his investment holdings in countries like Switzerland and Bermuda.

Romney said Friday during a blitz of television interviews that he would not be releasing any more tax returns beyond the 2010 return he has already released and the 2011 return he plans to release before the election. He has stayed firm on that stance over the past few days.

"In the political environment that exists today, the opposition research of the Obama campaign is looking for anything they can use to distract from the failure of the president to reignite our economy," Romney told The National Review's Robert Costa on Tuesday. "And I’m simply not enthusiastic about giving them hundreds or thousands of more pages to pick through, distort, and lie about."

But even prominent conservatives have called on Romney to release his returns in recent days, including Alabama Gov. Robert Bentley and conservative commentators George Will and William Kristol. Former Republican presidential candidate Ron Paul told Politico on Tuesday that Romney should release his returns.

But significantly, while most voters think he should release his tax returns, the poll doesn't measure the issue in terms of its importance or its effect on support.