The Corner on National Review Online: "[Ramesh Ponnuru] Michael Crowley argues ... that the Club for Growth is hurting the Republican party by backing primary candidates who can't win the general election. The Club, which has ties to NR in the person of Dusty Rhodes, would presumably reply: So what? It doesn't exist to help the Republican party. "
So what? Simple: if it hurts the Republican Party, it tends to help the Demnocratic Party.
I don't know what they call this in the Halls of Power, but down on the ranch we used to call that "stepping on one's own wee-wee."