Democrats are mostly exulting today at the news that longtime Pennsylvania Senator Arlen Specter will leave the Republican Party to caucus with them and run for his seventh term as a Dem next year. It's not hard to understand why they're pleased, nor why Specter made the switch. But I think the fact that he's leaving the Republicans suggests something about our politics that should trouble anyone with a stake in the system's success: it's now evidently impossible to be a Republican if you deviate from the party line in any significant way. Or as Glenn Greenwald (no fan of the move, by the way) put it:
The G.O.P. now resembles a religion more than a political party, where any deviance from established dogma is considered heresy that warrants excommunication. Its collapse into a Southern regional party has taken one large step forward. It is remarkable to watch an already marginalized party purposely shrink itself further.
The somewhat misleading math of "60 Senators to cut off debate" aside, I think it could easily be argued that the country, if not the Democrats themselves, is better off with someone like Specter remaining among the Republicans. The Senate runs on compromise, and as frustrating as they might be, the moderates in both caucuses usually drive those compromises. There are now perhaps five Republican Senators--Snowe, Collins, McCain, Voinovich, and Lugar--whom Democrats could even reasonably approach on this or that issue to cut a deal. But even those five will come under that much more pressure not to compromise in a smaller but more ideologically "pure" party.
For their part, the Democrats are likely to find that their caucus becomes exponentially less manageable as it expands. Whereas Specter before could extract concessions as a possible crossover vote to invoke cloture, as on the stimulus measure, he will now do so from inside the tent--and he'll be joined by as many as a dozen other Democratic Senators asking why the noob should get more deference than they. Given the difficulties that congressional party leaders already have endured (or as some might put it, caused) in advancing Obama's agenda, another unreliable vote could cause more harm than good.
The bigger problem, however, is with the Republicans. It's sad, but not surprising, that the most common reaction from the rightward side of the political spectrum to today's big news has been "good riddance." And it's not just from irate bloggers or grass-roots activists, either; Republican Sen. Jim DeMint stated that he would rather have 30 reliable-voting Republicans in the Senate than 60 "who don't have a set of beliefs." Among the Republicans, it's clear that ideological purity now runs far ahead of actual influence on the policymaking process.
But one of the ironies of Senate problem children like Specter and--it must be said--Joe Lieberman is that even as they frustrate colleagues and infuriate party loyalists, they see themselves as principled iconoclasts--public servants who consider each issue on its merits rather than merely deferring to the party leaders. As individuals, I find them both pretty loathsome; Lieberman's dishonesty and sanctimony are well established, and Specter looks today like an enormous hypocrite as well as a craven opportunist. (Which he is: he actually jumped in the other direction 43 years ago.) At the same time, though, their "unpredictability" might be more admirable, and is almost certainly closer to how the Founders imagined that the Senate should function, than the increasingly common party-line voting on both sides.
Perhaps the biggest difference between the two parties today is that the Democrats now tolerate heterodoxy on a wide range of issues, while the Republicans do not. The concern now is that the Democrats will (further?) abandon their principles in favor of holding onto power, while the Republicans already have abandoned everything but a very parochial interpretation of their own.