Public Policy Polling in Raleigh, N.C., said a poll it conducted found Clinton, the U.S. Secretary of State, the front-runner among Democrats, with 57 percent. Vice President Joe Biden is second at 14 percent, followed by Elizabeth Warren, who is running for the U.S. Senate in Massachusetts this year, at 6 percent, New York Gov. Andrew Cuomo at 5 percent, Russ Feingold, a former U.S. senator from Wisconsin, at 3 percent, U.S. Sen. Mark Warner of Virginia at 2 percent, and Maryland Gov. Martin O'Malley and Montana Gov. Brian Schweitzer at 1 percent each.