The Rasmussen Reports poll gives Udall a slim two-point lead over Schaffer, 46 percent to 44 percent. Rasmussen gave Udall a six-point lead in its survey a month ago, and the survey’s authors said the latest numbers suggest the race is tightening. The telephone survey of 700 likely voters was conducted Tuesday and has a margin of error of plus or minus 4 percentage points.

Udall has been the subject of an expensive negative ad campaign, largely paid for by independent issue groups allied with Republicans.

While the Rasmussen poll suggests those attacks are working, Udall spokeswoman Tara Trujillo noted that other polls indicate otherwise.

“We’ve always said this will be a competitive race, but we believe Mark’s message of standing up for Coloradans is getting out there,” Trujillo said. Michael Riley, The Denver Post