[A]ny analysis of this question has to start with the obvious truth that a clear supporter of abortion rights (or opponent of the "New Federalism" or whatever) is not on the table. I feel like I've been having the same argument since several smart people I know decided to vote for Nader in 2000, but the belief that the Democrats can somehow stop Bush from appointing a bad judge if they just try really hard is precisely equivalent to Bush's assertion that we can have a stable pluralistic liberal democracy in Iraq if we just try really hard. The Democrats may be able to stop an individual bad nominee--maybe two--but there are no circumstances under which you're getting a nominee who clearly supports progressive jurisprudence, even if it's confined to a narrow set of issues like abortion rights. "Bush's nominee" vs. "somebody you would actually want to see on the court" is a false choice; any chance of the latter ended when Bush was re-elected. The decision to be made about Miers has to be made by weighing the probabilities involved among bad choices. So once we accept the real dilemma, what do you think is better for progressives:

1)Is it better to have an ambiguous candidate who may be thought a wingnut, or get an Owen and remove all doubt?
2)Is it better to have somebody at/over or under 60?
3)Is it better, given the inevitability of a conservative nominee, to have a lightweight who will pass without much of a mark or somebody who will write lots of persuasive opinions and leave her stamp on constitutional doctrine for generations?

In all 3 cases, I think, you have to go with what's behind door #1, and that's Miers. Spending capital to reject Miers can only lead to someone who is some combination of more unambiguously conservative, younger, and more likely to leave a mark on the court's doctrine. I can't see any way it's in the interests of progressives to pull out the stops to block Miers. Miers could, of course, be just as awful as Owen, Brown or Luttig, but even if she is you're not really any worse off.

[...]

Look at it this way. If the Court overturns Roe and strikes down the Endangered Species Act and expands its claim that state universities should have the same legal immunities as 16th century British monarchs and further guts habeas corpus, are you going to be consoled by the fact that the opinion in question is really well-crafted? I won't. And rejecting Miers can only make these outcomes more likely.

(That Scott can think so clearly as demonstrated here, despite being a Red Sox fan and picking the Angels to beat the Yankees, is very much to his credit.)

There's also a third alternative that Senate Democrats can take: not to support Miers or fight against her, but to more or less abstain from the process and let her pass on Republican votes. I'm not saying that they shouldn't press Miers at the confirmation hearings (although it looks at the moment as if the Republican contingent will do so on ideological grounds), especially on the question of her qualifications to be an Associate Justice of the United States Supreme Court, but absent a smoking gun or a clear indication that she's a dingbat wingnut (neither of which are likely), there's no reason that the Democrats need to go one way or the other on this. Let the GOP take the responsibility for her, she's the creature of their President.

Update (10/27): David Corn agrees:

Here's an idea that I reserve the right to reject upon further reflection: Democrats in the Senate should vote "present" on the Miers nomination. It's not an aye, and it's not a nay. They could argue that they believe this is a sub-standard nomination that deserves no one's support but that they do not want to provide Bush the opportunity to satisfy those who are calling for a right-wing jurist who will decisively steer the court further in a conservative direction. Facing two awful options--both bad for the nation--Democrats can assert that they will be party neither to Bush's cronyism nor to Bork's crusade. Let the Republicans slug it out and bear responsibility for the consequences.

Oh, some cranky think-tankers and commentators will call this a cop-out, a dereliction of constitutional duty. But why validate--or be used by--either side in the Republicans civil war? Once in a while, the correct response to a situation is, don't just do something, sit there.