structural:scholar_edition
The emergence of cloture (1917–1969)

In 1949, in response to filibusters of amendments to the Journal and motions to proceed to the consideration of bills, the cloture rule was amended to allow cloture to be filed on "any measure, motion, or other matter pending before the Senate, or the unfinished business". The Senate simultaneously made invoking cloture more difficult by requiring two-thirds of senators duly chosen and sworn to vote in favor of a cloture motion. Future proposals to change the Senate rules were specifically exempted from being subject to cloture.: 191