[Gondring]

I'd also add that it was a Democrat-controlled Senate that used a simple majority to change the rules 30 years ago to make it "three-fifths" of "all elected Senators" instead of "two-thirds" of Senators "voting and present" required to end a filibuster.

This provides a disincentive to debate--meaning it's easier to obstruct now by just walking out and removing quorum, rather than requiring the minority to continue to debate any points of contention. This is hardly what the Founding Fathers intended.

[Cboldt]

RULE VI
QUORUM - ABSENT SENATORS MAY BE SENT FOR

1. A quorum shall consist of a majority of the Senators duly chosen and sworn.

2. No Senator shall absent himself from the service of the Senate without leave.

3. If, at any time during the daily sessions of the Senate, a question shall be raised by any Senator as to the presence of a quorum, the Presiding Officer shall forthwith direct the Secretary to call the roll and shall announce the result, and these proceedings shall be without debate.

4. Whenever upon such roll call it shall be ascertained that a quorum is not present, a majority of the Senators present may direct the Sergeant at Arms to request, and, when necessary, to compel the attendance of the absent Senators, which order shall be determined without debate; and pending its execution, and until a quorum shall be present, no debate nor motion, except to adjourn, or to recess pursuant to a previous order entered by unanimous consent, shall be in order.

http://rules.senate.gov/senaterules/rule06.htm