FYI this is not always the case - a senator can vote for consideration (which regular session rules require a 2/3 vote) on a bill and then vote against it for passage (passage only requires majority). This parallels the US Senate filibuster process.2firfun50 wrote:
Since by rule, all bills passing the Senate in regular session require 2/3 majority, only the house passage would be in question.
In practice, many times you will see >2/3 support on the final Senate vote because they will not take up contentious ones...but this isn't guaranteed.