Mitt Romney tried again on Thursday to shift the campaign conversation away from his refusal to disclose more of his tax returns, raising questions about what may be in them.
While Romney accused President Barack Obama of demonizing business success by hounding the Republican challenger over the issue, tax experts were speculating about what might be in Romney's undisclosed returns.
So far he has released only his 2010 return and a draft of his 2011 return. He has pledged to release the full 2011 return when it is ready. He has also made disclosures to election officials that shed some light on his personal finances.
Formerly governor of Massachusetts, Romney co-founded private-equity firm Bain Capital, a highly successful investment house, and is one of the wealthiest individuals ever to run for the White House.
Presidential candidates are not required to disclose their tax returns, but it has become common practice. Romney's father released 12 years of returns when he ran for president in 1968.
"The number everyone is focused on is, of course, the effective tax rate," said University of Notre Dame accounting professor Brad Badertscher.