There were a number of confirmation hearings in the Senate where Mike Pence, as President of the Senate, cast the tie-breaking vote. That part is clear to me from the Constitution.

Impeachment is also in the Constitution. The Senate shall have the sole Power to try all Impeachments . . . And no Person shall be convicted without the Concurrence of two thirds of the Members present.

Recently there have been some confirmation votes that were 50-49 and Pence was not required to vote which implies that just a majority of those voting were required for confirmation.

And recently there has been talk that 60 votes are required for funding a border wall. I think that is requirement due to Senate rules on budget measures—not something in the Constitution. Other than budgets, does anything else in the Senate require a cloture vote?

There was a noteworthy incident a while ago where all of the state senators left the state so that there wouldn’t be a quorum. Is a quorum required for anything in the US Senate?

So what are the rules for deciding votes in the Senate and where do they come from? Is it a simple majority of members or the majority of those voting? How does voting present impact the result? Are the rules the same for confirmation votes as for voting on bills?

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    I'm migrating this to Politics:SE since it doesn't actually appear to be about History per se.
    – sempaiscuba
    Commented Dec 12, 2018 at 21:16

2 Answers 2


The majority of those voting "yes" or "no" is sufficient to pass something in the Senate. People voting "present" do not count.

This is illustrated by the longstanding (but rare) practice of "pairing" -- see footnote 23 of this Congressional Research Service publication -- in which, when a member is absent, he/she will sometimes find a member who would have voted the opposite way, and they will make a deal for the attending member of the pair to vote "Present" so that the result is not changed by the absence of the other member of the pair. The most recent high-profile use of this custom was during the Kavanaugh confirmation vote, in which Sen. Murkowski agreed to vote "present" (rather than "no") so that a Kavanaugh supporter (a "yes") did not have to miss his daughter's wedding to attend the vote.

51 Senators (a majority of the entire Senate) constitute a quorum. This number would change if there were a vacancy. See the Senate rules.

60 Senators (three-fifths of the entire Senate) are sufficient to stop debate on a question -- again, presuming there are no vacancies. You are correct that this is fixed by Senate rules. You are not correct that this has to do with budget matters; it has to do with virtually all Senate business until recently, and still with most Senate business -- at least as of today. There has been a longstanding threat by the Republican majority (and President Trump) to further change the rules (known as the "nuclear option"); both Democrats and Republicans have recently used this option to end filibusters for executive branch and lower court nominees (Democrats) and Supreme Court nominees (Republicans).

When there is no quorum present in the U.S. Senate, the only things that are allowed are 1. a vote to adjourn, and 2. a vote to direct the Sergeant-At-Arms to try to round up Senators. No other business may be conducted. See, again, the Senate rules.

Because two-thirds of Senators are required to convict an impeached president, the cloture rules would very likely be irrelevant to that -- it would require more votes to convict than to end debate, so if the votes were available to convict surely the same Senators would vote to end debate.

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    Your description of a quorum in the Senate ignores standing Supreme Court precedent, which is basically that the Senate has a quorum whenever it says it does in accordance with its own rules. Legislation has been passed with less than the majority of senators present and upheld in the courts. Basically, if no senator actually requests that the presence of a quorum be checked, then the Senate has a quorum by default. This is one of the things that would stymie attempts of one party to not attend a split Senate: the other party would simply not invoke the quorum check. Commented Dec 12, 2018 at 23:11
  • Yes, it is true that the Senate rules dictate a particular procedure for determining whether there's a quorum, and if no one invokes it, there's a quorum. But the rules say a quorum is 51 members (or rather a majority of all members). If someone invokes that procedure, if there are 51 senators, there'll be a quorum, and if there aren't, there won't be. Commented Dec 13, 2018 at 12:14
  • "Because two-thirds of Senators are required to convict an impeached president, the cloture rules would very likely be irrelevant to that": I think the cloture rules are irrelevant not for that reason but because there is no provision for debate in the rules governing the procedure of impeachment trials
    – phoog
    Commented Dec 13, 2018 at 19:32

The US Senate used to have a rule that, once "debate" had started on a bill, anyone who had the floor got to keep it as long as they continued to use it. The only way to take it away from someone who didn't want to yield (and continued to talk) was with a 2/3rds vote of the Senate. Purposely doing this just to stop the Senate from moving on a bill you don't like was called a filibuster.

During the Civil Rights era, filibusters were used by the White Supremacist southern Democrats to prevent any civil rights legislation from passing. This becoming routine got to be a real problem, because it prevented the Senate from getting anything done.

So a compromise was reached, and the vote threshold for ending "debate" on a bill was reduced from 66 votes to 60. In exchange, the rule was also changed so that the filibustering senators didn't have to actually stand up and talk the entire time this is going on. The Senate could just move on to other matters and let the bill languish in "debate" forever.

So now, as per Senate rules, most bills require 60 votes to end debate and have an actual vote. But again, this is just a Senate rule, and rules can be changed with a simple majority. This has happened multiple times recently where the threshold for ending debate on various kinds of judges was lowered to a simple majority. It could be done with other legislation too, if the Senate majority feels like doing so.

  • Wasn't it 67 votes? 66 is less than 2/3 of 100.
    – phoog
    Commented Dec 13, 2018 at 19:34
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    In fact, I now know that the former rule required 2/3 of votes cast, so it could even be fewer than 66 if there were enough absences, whereas the current rule requires 3/5 of senators seated, so absences don't make a difference, but the required number is lower than 60 if there are two or more vacant seats. Also, I remember senators actually physically holding the floor in the 70s or 80s, so (if my memory serves me) the abolition of that requirement must have been rather later than the change from 2/3 to 3/5.
    – phoog
    Commented Sep 29, 2021 at 11:43
  • @phoog - It hasn't been the rule since 1970. I have a vague memory from a few years back of someone doing something similar as sort of a publicity stunt, but it hasn't been required to stop a bill in the Senate since then. There are some floor-holding tricks I've seen employed in The House, but those can't really be used indefinitely.
    – T.E.D.
    Commented Sep 29, 2021 at 16:23
  • Maybe so. I thought I remembered some phone-book readings in my youth, but it's also possible that they were described to me by someone who didn't know that the rules had changed. But then again, at thoughtco.com/filibuster-rules-of-the-us-senate-3368318, you can read "2013: Republican U.S. Sen. Rand Paul of Kentucky filibusters for nearly 13 hours to question and raise awareness of the U.S. government's use of drones. It is the ninth-longest filibuster in history. "I will speak until I can no longer speak," he said. Paul ended his filibuster because he had to go to the bathroom."
    – phoog
    Commented Sep 29, 2021 at 18:27
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    @phoog - Yup "...to raise awareness.." = publicity stunt.
    – T.E.D.
    Commented Sep 30, 2021 at 13:05

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