Clinton, who has said she isn't interested in seeking the nomination, would capture 65 percent of the Democratic vote, compared to Vice President Joe Biden's 13 percent, results of the poll released Thursday indicated.
New York Gov. Andrew Cuomo would draw 4 percent, and Massachusetts Gov. Deval Patrick, Maryland Gov. Martin O'Malley and Virginia Sen. Mark Warner would pick up 1 percent or less, results of the national showed.
If she doesn't run, Biden would have nearly as large a lead over the rest of the potential field, Quinnipiac said. Biden would get 45 percent, with 15 percent for Cuomo, 6 percent for Patrick, 3 percent for O'Malley and 2 percent for Warner.
"Former Secretary of State Hillary Clinton has a rock-solid hold on the hearts of Democratic voters at this point," said Peter Brown, assistant director of the Quinnipiac University Polling Institute in Hamden, Conn. "If she decides not to run, Vice President Joseph Biden does almost as well as she does against the rest of the field. There is a long way to go until 2016, but none of the other younger potential candidates for the Democratic nomination currently has anything approaching widespread support from party voters."
Results are based on telephone surveys of 1,471 registered voters April 25-29. The margin of error is 2.6 percentage points.