CHARLOTTE, N.C. — U.S. Senate Majority Leader Harry Reid of Nevada on Tuesday continued his relentless campaign to push Republican presidential nominee Mitt Romney to release more of his tax returns, telling Democratic National Convention delegates that Americans still don’t know who Romney really is.

“Never in modern American history has a presidential candidate tried so hard to hide himself from the people he hopes to serve,” said Reid, a Democrat and Nevada’s senior senator. “When you look at the one tax return he has released, it’s obvious why there’s been only one.”

Reid said Romney’s 2010 return showed that he paid a lower tax rate than middle-class families and that “he chose Swiss bank accounts and Cayman Island tax shelters over American institutions.”

“And we can only imagine what new secrets would be revealed if he showed the American people a dozen years of tax returns,” Reid said.