Clinton, who plans to step down as secretary of State at the end of President Obama's first term, has repeatedly denied her interest in mounting another presidential campaign.
Last month, she told Marie Claire magazine that while she would be "up there cheering" for the first female president, that candidate would not be her.
"I have been on this high wire of national and international politics and leadership for 20 years," she told the magazine. "It has been an absolutely extraordinary personal honor and experience. But I really want to just have my own time back. I want to just be my own person. I'm looking forward to that."
Still, polls conducted earlier this month by Public Policy Polling showed Clinton would easily be the favorite to sew up the Democratic nomination, with the secretary of State leading contenders like Vice President Biden and New York Gov. Andrew Cuomo in early voting primary states like Iowa, New Hampshire and Florida.