The latest Rasmussen survey on the Colorado Senate race shows insurgent candidates making gains in a hypothetical general election.
The poll, which surveyed 500 Likely Voters in Colorado on June 7, showed Weld County DA Ken Buck defeating incumbent Democrat Michael Bennet 46% to 41%. Buck's Republican rival, Jane Norton, is beating Bennet by roughly the same margin.
The poll showed Buck, however, with a 45% to 39% over Bennet's Democratic challenger, former State House Speaker Andrew Romanoff. Norton and Romanoff were roughly tied.
Bennet's numbers against Norton and Buck have stayed relatively constant over the last two months.
Each monthly Rasmussen poll has had a margin of error of 4.5%.
The parties will choose their nominees in primaries on August 10.