Colorado senator Mark Udall, a Democrat first elected in 2008, is in a statistical tie with Republican challenger Cory Gardner, according to a new poll from Rasmussen Reports.

The survey of likely voters in Colorado found 42 percent support Udall, while 41 percent support Gardner, a two-term congressman. Thirteen percent remain undecided.

Gardner's recent entry into the Senate race caused two other GOP candidates to drop out. Meanwhile, Udall has seen weak polling numbers in recent weeks, and Obamacare, for which he voted, has increasingly poor support in Colorado.

Next Page