Just in case anyone feels like getting into details, I wrote a longish account of all the ways in which it has traditionally been possible for Senators to block a judicial nominee
here. The key points:
According to the Judiciary Committee Rules, a nomination cannot be reported out of the Committee without at least one affirmative vote by a member of the minority party. So if the minority unanimously opposes a nominee, it dies. However, Orrin Hatch overrode this rule early in 2003. A good statement on the topic from Senator Leahy is here; it includes quotes in which Hatch expresses support for this rule before 2003.
Also, Hatch tossed out the policy according to which any Senator from the home state of a nominee could veto that nominee in 2001, and started allowing nominations to go forward even if both of the home state Senators were opposed in 2003.
Frist, Santorum et al are
wrong when they say that the filibuster has never been used against judicial nominees before. But one of the reasons why there have not been more filibusters of judicial nominees in the past is that there used to be a lot of other, easier ways of killing a nomination, even if you were in the minority party. Since 2003, the GOP has eliminated all those other ways. The filibuster is the last one left.
Details in the post at Obsidian Wings. I also wrote a long thingo about the Senate Rules and the Constitutional questions raised by the nuclear option here, if anyone's interested.