WASHINGTON (CNN) -- Sen. Hillary Clinton of New York retains her position firmly at the front of the pack of Democratic presidential candidates, with a poll Thursday giving her 44 percent of the vote, nearly double the 24 percent garnered by the next-closest candidate, Sen. Barack Obama of Illinois.

Former Sen. John Edwards of North Carolina was favored by 16 percent of the 458 registered voters who described themselves as Democrats or as independents who lean Democratic.

New Mexico Gov. Bill Richardson followed with 5 percent, Sen. Joe Biden of Delaware attracted 3 percent and Rep. Dennis Kucinich of Ohio won 2 percent. Sen. Chris Dodd of Connecticut and former Sen. Mike Gravel of Alaska each attracted less than one half of one percent.

While Clinton appear to be firmly entrenched as the front-runner, there is one important warning sign for the Clinton campaign.

Among Democrats who did not graduate from college, she leads Obama by 26 points, but among Democrats with a college degree, Clinton has only a three-point edge.

Turnout is much higher among college graduates, particularly in the primary season, so the Clinton camp may have to work harder to turn her lead in the polls into victory at the ballot box.

A Washington Post/ABC News poll of Iowa voters released on August 3 had Clinton, Obama and Edwards in a virtual tie in that key early caucus state. Obama led with 27 percent, while Clinton and Edwards both had 26 percent.

The CNN/Opinion Research poll, which had a sampling error of plus-or-minus 4.5 points, was conducted August 6-8 and involved telephone interviews with 1,029 adults.

Since June, no candidate's support has changed by more than one point. E-mail to a friend

CNN Polling Director Keating Holland contributed to this report.

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