Frum answers Erick Erickson's attack:
As many political scientists have demonstrated, the parties are becoming more polarized even though the electorate is not. The cause of the “disconnect” (as Morris Fiorina calls it)? Party elites, both Democratic and Republican, have found ways to take command of party institutions and steer their organizations further and further away from the broad preferences of the country. Activists wish their parties to be as conservative (or as liberal) as they can get away with and voters are confronted at election time with the job of deciding which of two unappealing alternatives is the less obnoxious. It’s endlessly ironic to me that the people most enthusiastic about commandeering parties in this way will describe themselves as “populist” and condemn as “elitist” those who think that good politics tries to solve the problems that most voters regard as most important.
Chait thinks extreme partisanship is inevitable. Jonathan Bernstein doesn't.