How Measures Are Brought to the Senate Floor: A Brief Introduction [April 6, 2017] [open pdf - 502KB]
From the Summary: "Two basic methods are used by the Senate to bring legislation to the floor for consideration: (1) The Senate, at the majority leader's request, grants unanimous consent to take up a matter, or (2) it agrees to his motion to proceed to consider it. Because the motion to proceed is subject to debate in most circumstances, it is less frequently used. Both methods are derived from the basic premise that the Senate as a body may decide what matters it considers. The Senate may also use the same two methods to bring up executive business (nominations and treaties). This report will be updated to reflect changes in Senate practice."
CRS Report for Congress, RS20668
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html