What is Senator Clinton hiding?

An excerpt from the Chicago Tribune:

In politics, honesty is not always the easiest policy. Barack Obama got a reminder of that when he released a list of "earmark" expenditures he has proposed -- including a $1 million request for the University of Chicago Medical Center, where his wife, Michelle, is a vice president. In his meeting Friday with the Tribune editorial board, Obama indicated that he should have left that item to fellow Illinois Sen. Dick Durbin, but he's willing to disclose it and be held accountable.

Hillary Clinton, by contrast, often seems to operate by the maxim that silence is golden. When asked whether she would release a list of her earmarks, her spokesman dodged the question, while declaring that she is "proud of the investments in New York that she has secured." But for now, at least, not proud enough to let voters know what they are.

This exercise in secrecy is part of a Clinton pattern that grows more worrisome all the time. The former first lady often says that she, unlike Obama, has been thoroughly vetted, rendering her impervious to Republican attacks. In fact, there are some important things unknown about her -- and her conduct suggests she wants to keep it that way. Which raises a question for voters: What is she hiding, and why?