the senate changed to 60 votes in 1975.
when did the senate changed to 60 votes?
1975
in 1975, the democratic senate majority, having achieved a net gain of four seats in the 1974 senate elections to attain a strength of 61 (with an additional independent senator caucusing with them for a total of 62), reduced the necessary supermajority to three-fifths (60 out of 100). however, as a compromise to those who were against the revision, the new rule also changed the requirement for determining the number of votes needed for a cloture motion's passage from those senators "present and voting" to those senators "duly chosen and sworn". thus, 60 votes for cloture would be necessary regardless of whether every senator voted. the only time a lesser number would become acceptable is when a senate seat is vacant. for example, if there were two vacancies in the senate, thereby making 98 senators "duly chosen and sworn", it would take only 59 votes for a cloture motion to pass.
cloture
with democrats having lost a filibuster-proof supermajority in the senate, but having already passed the senate bill with 60 votes on december 24, the most viable option for the proponents of comprehensive reform was for the house to abandon its own health reform bill, the affordable health care for america act, and pass the senate's bill, the patient protection and affordable care act, instead. various health policy experts encouraged the house to pass the senate version of the bill. however, house democrats were not happy with the content of the senate bill, and had expected to be able to negotiate changes in a house–senate conference before passing a final bill. with that option off the table, as any bill that emerged from conference that differed from the senate bill would have to be passed in the senate over another republican filibuster; most house democrats agreed to pass the senate bill on condition that it be amended by a subsequent bill. they drafted the health care and education reconciliation act, which could be passed via the reconciliation process. unlike rules under regular order, as per the congressional budget act of 1974 reconciliation cannot be subject to a filibuster, which requires 60 votes to break, but the process is limited to budget changes; this is why the procedure was never able to be used to pass a comprehensive reform bill in the first place, such as the aca, due to inherently non-budgetary regulations. whereas the already passed senate bill could not have been put through reconciliation, most of house democrats' demands were budgetary: "these changes – higher subsidy levels, different kinds of taxes to pay for them, nixing the nebraska medicaid deal – mainly involve taxes and spending. in other words, they're exactly the kinds of policies that are well-suited for reconciliation."
history of health care reform in the united states