A week after CNN brought him on to act as a kinder, gentler conservative voice, David Frum has resigned from the public radio show Marketplace. Frum acted as the conservative counterpart to liberal former Secretary of Labor Robert Reich. In his resignation note Frum explains that he no longer feels comfortable representing a right-wing constituency.

But on the issues that today most passionately divide Americans – healthcare reform, monetary policy, social spending to aid the unemployed, and – soon – the American response to the euro crisis, I have to recognize that my views are not very representative of the conservative mainstream.

Accordingly, I have resigned my role on the Marketplace program, nominating potential replacements from closer to the present GOP consensus. I may not agree with that consensus, but I cannot deny its existence and importance.

When Frum joined CNN, The Atlantic Wire's John Hudson asked if he would be an acceptable conservative voice at CNN: "The question is: will the right want him in that conversation?" Frum's answer, at least for public radio, appears to be no.