For senators who are principled, the question is about his qualifications, and they should vote.
But for democrats who are going to vote strictly based on how it will effect their next election, they have to figure out which vote is worse for them. If they vote against Alito, they MIGHT get hurt by moderates who disagree. Moderates will disagree more or less based on how the media covers this. If the media keeps saying Alito sounded rational, answered questions, and looks like a good justice, moderates will punish democrats. If the media decides Roe is worth being partisan, the moderates might think the democrats are saving the country.
The couple of democrats left who are from red states will vote to end the filibuster, but we already got rid of half of them. I say that because in a few races a large turnout by angry republicans could throw someone like Daschle out. But there are only a couple left like that.
So the democrat senators have to weigh that risk, against the clear danger of going against the democrat base. MoveOn has called for a primary opponent against Lieberman over his support for the war. Surely any senator up for election this year in a blue state has to worry about being targetted in a primary, or having their legs cut out in a general election.
Lautenberg may have to support a filibuster for that reason. Menendez as well. Even the red-state senators might be worried that losing democrat support could lose them their seats.
So, how do you think they'll see this, given it is a Supreme Court nomination, not just appeals court. Are they more afraid of what moderates, independents, and rabid republicans will do to them, or are they more afraid of their base.
The answer to that is to look to Leiberman's race. The new polling data suggests that Leiberman did lose support from Liberals for his stance on the war. Interesting development is that Republicans made up the difference.
The reality is that Democrats have voted third Party. 2000 for example. But they only did so because they didn't believe their votes were needed. When they do believe their votes are needed to keep Reps/conservatives out they vote for Dems. Whereas Republicans have a history of actually sitting out/voting third party in elections where they know their votes are vital such as in '92. If I'm a Dem strategist I calculate the Hard Left is all Talk. they won't sit out '06, because they hate us too much. Therefore cater to the moderates/Indy's/Conservatives Dems that can be persuaded to vote Rep. Republicans on the other hand need to fixate on their base, because there base has shown they don't value power enough if they believe Republicans must be taught a lesson.