Via The Political Wire:
In the 1990s we saw the defection of many a conservative Democrats to the Republicans as the South finished realligning. There are a few left, but they will probably survive until retirement and then be replaced by Republicans.
The second part of that process started with Jim Jeffords. Slowly liberal/moderate Northeastern or Midwest Republicans will begin to change party affiliations or when they retire their seats will go Democratic. The challenge for any party is to slow those defections so they occur after they have little impact. A really bad way to stem that sort of thing is to deny moderates important chairmanships. Chris Shays seems like an unlikely defector, but this isn’t a good strategy for the Republicans because it tells other moderates that if they stick to their guns, they won’t get to be Chairs providing little incentive to stick it out.
At least if you are going to piss off the dissidents, do it like Clinton did to Shelby and have fun sticking a shiv in the guys back. Another example of this is Jim Saxton being denied the Chairmanship of House Resources.