With an anti-incumbent mood still festering, Colorado Democrats might be better off nominating former House Speaker Andrew Romanoff instead of Sen. Michael Bennet, according to a new survey commissioned by American Crossroads. 

Public Opinion Strategies conducted the survey for the conservative activist group, which is headed by former Republication National Committee Chairman Mike Duncan. It polled 13 states with Cook Report-defined competitive Senate races in an identical fashion to the methodology used in the NPR poll from June.

The troubling news for Bennet — and other Democratic incumbents — is that only 42 percent of the Colorado voters polled approve of him, and 44 percent disapprove. Moreover, asked whether they wanted to elect a new person or reelect their incumbent, just 34 percent would vote for their incumbent, while 55 percent prefer a new person.

The survey also found Democratic Sens. Blanche Lincoln (Ark.), Patty Murray (Wash.) and Harry Reid (Nev.) face similar headwinds. "While some of the Democratic candidates in these 13 Battleground Senate states may survive, given the way the electorate is moving against them, most of them will not," pollster Glen Bolger wrote in the survey memo.

Asked to rate a match-up between a "Democrat" and a "Republican" — because there were no clear primary front-runners — Colorado respondents favored the Republican by a 47-to-40 percent margin. Republicans Ken Buck and Jane Norton are competing for the GOP nod.

The poll, conducted Aug. 2-5, has a margin of error of 2.72 percent.