WHO’S THE FAIREST OF THEM ALL?….Ezra Klein thinks John McCain is a real conservative. Jon Chait thinks he’s more liberal than Ezra lets on. I’m more on Ezra’s side than Jon’s ? and I think Ezra’s case would have been even stronger if he’d taken into account McCain’s relentless hawkishness ? but I was interested in this passing comment from Jon over at The Plank:

Ezra cites McCain’s ACU ratings. But I think that, especially in recent years, those ratings do a lousy job of showing who’s liberal and who’s conservative. Don’t they show Hillary Clinton to be one of the most liberal Senators? There’s an article to be done debunking those ratings, but I’m guessing that the changing partisan dynamics of the current era has rendered the old system worthless.

The same thought has crossed my mind too, though I’ve never mustered the energy to really investigate it. But I think there’s something to this. We’re now living in an era in which liberals have pretty much all sorted themselves into the Democratic Party and conservatives into the Republican Party, and party discipline has increased to the point that we largely live under a de facto parliamentary system: most of the time, you just vote with your party. Opportunities to jump ship are increasingly few and far between.

This doesn’t mean the rankings are useless, but I’ll bet they’re getting pretty close. I have a feeling somebody ought to be looking at a different way of determining just who the most liberal and conservative members of Congress are.