Rep. Cory Gardner (R-Colo.), left, and Sen. Mark Udall, (D-Colo.) (AP)

Sen. Mark Udall (D-Colo.) is in a neck-and-neck race against Rep. Cory Gardner (R), according to a new poll released Thursday.

The Quinnipiac University survey of the Colorado Senate race shows Udall with a 45 percent to 44 percent lead over the Republican, well inside the margin of error. There is a big gender divide, with Udall winning a majority of women and Gardner carrying a majority of men surveyed.

President Obama's image in the state is struggling and so is the image of the federal health-care law. Voters disapprove 59 percent to 38 percent of the job Obama is doing, which should come as a troubling sign for Udall's campaign.

Gardner entered the race earlier this year and cleared the GOP field in a hurry, boosting Republican hopes of picking up a seat that had looked out of reach.