When it comes to the filibuster and cloture, when 100 Senators are voting, it takes 60 Senators to limit debate. What about when fewer than 100 Senators vote? If, for example, only 70 Senators vote, does it still require 60 votes to limit debate, or only 42 (3/5s of 70)? — asks John, 61, from Colorado.
Under Senate Rule XXII, limiting debate to end a filibuster requires the approval of three-fifths of the “constitutional membership of the body” — meaning, three-fifths of the 100 elected senators — rather than three-fifths of the senators present and voting.
So, 60 of the “duly chosen and sworn” senators have to vote affirmatively to limit debate and end a filibuster.
If 30 senators are opting not to vote — which, though possible, is highly unlikely — then the procedure simply remains stalled. Debate can be indefinitely delayed until at least 60 senators vote affirmatively.