John Frank --- The Denver Post
A new Denver Post poll shows Colorado's marquee U.S. Senate race is shifting toward Republican Cory Gardner, as President Barack Obama's sagging popularity erodes the advantage once held by Democratic U.S. Sen. Mark Udall.
Gardner and Udall remain in a tight race, 45 percent to 43 percent, according to a SurveyUSA poll of likely voters released Monday.
Gardner's lead is within the margin of error, making the race a statistical tie, but it represents a reversal from a month ago when Udall held a 4-point edge.
The Post poll — conducted Thursday through Sunday — had a margin-of-error of plus-or-minus 4.1 percentage points.
"There has been movement to Gardner that is unmistakable and what had been nominal advantage for Udall has been erased," said Jay Leve at SurveyUSA.
Gardner's momentum is evident in the underlying numbers.
A 10-point lead among independents in a September poll that favored Udall disappeared. It's now tied at 40 percent, the poll found. And a 13-point gap among woman that favored Udall is now seven points.
Both shifts came despite Democratic efforts to target these key swing voters by emphasizing social issues and painting Gardner as too conservative on abortion and birth control.
On the other side, Republicans attacks on Udall appear to be weakening his popularity. Udall's job approval is 36 percent compared to 53 percent disapproval, a 17-point negative gap, the poll found. A month ago his approval rating stood at negative six.