Clearly the abortion issue is very important in the debate over Samuel Alito's nomination to the Supreme Court, and it's a good reason to vote against him. But is it a good enough reason to filibuster?
After all, the filibuster is, most will agree, an extraordinary tactic to be used in extraordinary situations. A persuasive way to explain this is to say that while one might merely oppose his politics, his deference to the executive threatens to undermine democracy itself by removing a critical check on executive power in our system of checks and balances. When the rules themselves are at stake, extraordinary measures are appropriate.