Senate Rule XIV requires that measures be read twice on different legislative days (see "Adjournment and Legislative Days" section) before being referred to a committee. Most bills and joint resolutions, however, are considered as having been read twice and are referred to committee upon introduction. Under Rule XIV, when a Senator demands two readings and there is objection to the measure's second reading, the measure is placed directly on the Calendar of Business (see next section) without reference to committee.Additionally noted:
The Senate only has two calendars: the Calendar of Business (commonly called the "Legislative Calendar"), and the Executive Calendar. Nominations and treaties are referred to the Executive Calendar. Legislation reported from committee are referred to the Calendar of Business, or placed on this calendar by unanimous consent. As discussed earlier, Rule XIV provides a procedure for placing measures on the Calendar of Business without reference to committee.
Traditionally, bills presented by the minority party would be referred to a committee where it would die an un-eventful death because it would never make it back out of committee (kind of like an alternative filibuster). This little provision will allow Democrats to place bills directly onto the Senate floor where there would be an up or down vote. This means that every bill about health care, veterans benefits, education, etc, that the Republicans have been killing in committee would now have to be voted on. Every time the Republicans vote 'no' on funding head start, health care, etc, there is an official record of their vote that Democrats can use against them in the next election cycle.
As I said before in prior posts, the Republicans are getting greedy in this whole filibuster thing. It may just be there down fall.
Source: House and Senate Rules of Procedure: A Comparison