The Quinnipiac University Poll found 50 percent of those surveyed saying they would vote for Beauprez and 40 percent for Hickenlooper. More than three-quarters, 77 percent, say they are unlikely to change their minds before election day.
Two recent polls of registered voters showed the candidates in a statistical tie. A Denver Post poll, conducted two days before the Quinnipiac Survey, gave Hickenlooper 45 percent of the vote and Beauprez 43 percent, and an NBC/Marist survey early in September had similar results.
Quinnipiac found that two other candidates, Libertarian Matthew Hess and Green Party candidate Harry Hempy, would each pick up 3 percent of the vote.
Both Hickenlooper and Beauprez do well among voters from their own parties. Beauprez leads 50 percent to 37 percent among independents.
The candidates split the women's vote while men lean towards Beauprez.
"Colorado Gov. John Hickenlooper is behind the challenger on the key qualities voters want in a leader: honesty, caring and leadership," said Tim Malloy, the poll's assistant director. "Pundits were predicting that Gov. Hickenlooper faced a close race for reelection. Instead, he's got a mad dash to make up a double-digit deficit. The Democrat does not get the traditional strong support from women to offset Bob Beauprez's army of support from men."
Hickenlooper is one of a number of incumbent governors from both parties who are locked in close races or trailing in the polls.
The poll of 1,211 likely voters was conducted by telephone from Sept. 10 to Sept. 15. The margin of error is 2.8 percentage points.