The Senate is governed by the Constitution, the Standing Rules of the Senate, permanentStanding Orders of the Senate (adopted in prior Congresses), temporary Standing Orders of theSenate (adopted at the beginning of each Congress), and statutes. It is also governed by precedents,which are decisions made by the presiding officer of the Senate, or the body itself, concerning howits rules operate in practice. The precedents tend to elaborate the Senate's understanding of its ownrules. The Standing Rules, for example, can be printed in 78 pages, while the most recent collectionof Senate precedents is 1,564 pages long. Precedents have tremendous weight in decidingparliamentary questions in the Senate, and the presiding officer, whether the Vice President or amajority party Senator, is expected to be guided by these precedents when ruling on a pendingquestion. The Standing Rules of the Senate would seem to be the obvious place to start if a Senatordesired to change that chamber's procedures. If there is no substantial opposition, the Standing Rulesof the Senate can be changed by a simple majority vote; there is no supermajority requirement forchanging the rules. If, however, there is opposition to the proposed rules change and if opponentsseek to prevent a final vote on the proposal by extended debate and amendment, known as afilibuster, a supermajority requirement does exist for invoking cloture, or ending debate, on a ruleschange. Senate Rule XXII, which sets out the process for invoking cloture, requires that two-thirdsof those present and voting (67 if all Senators participate) vote to invoke cloture on a rules change. This is a difficult threshold to meet; invoking cloture on all other measures or mattersrequires a three-fifths vote of all Senators chosen and sworn (60 votes, if no vacancies exist). Cloture on a proposal to change an existing Standing Order, or to establish a new Standing Order,also requires this lower threshold. It should be noted that the Senate uses Standing Orders to modifyor set aside its standing rules without doing so directly. S.Res. 445 , in the 108thCongress, for example, inherently superceded portions of Senate Rule XXV and Senate Rule XXVI,to establish a committee on Homeland Security and Governmental Affairs without directly amendingthe rules. A similar approach might be used to alter Rule XXII without directly amending it. The potential difficulty the elevated requirement for invoking cloture poses for changing theStanding Rules, has led some to look at making changes in Senate practice through proceedings thatalter existing precedents or establish new ones. Proceedings of this kind, it is argued, would bothbreak old precedent and establish new Senate precedents, and could have the effect of changingSenate practice. Eventually such a plan might even result in changes in Senate rules, whilecircumventing the procedures prescribed by Senate rules for changing the rules. Some have recently referred to such actions as the "nuclear option" for bringing about changein Senate rules or practice, referring to the possible problems that could result in the Senate from theuse of such tactics. No set definition exists for the term "nuclear option"; indeed, this term has beenused to refer to many kinds of possible proceedings. One set of possibilities, however, involvesappealing to constitutional requirements as an authority superior to that of the Senate's own rules,and supporters of such an approach have accordingly preferred to describe such an approach as a"constitutional option." (1) Much of the discussion of the "nuclear" or "constitutional" option has involved presidentialnominations, particularly those for the federal judiciary. Fights over the confirmation of judicialnominees are not a new phenomena, but the intensity and frequency of the confrontations haveincreased in the last decade or so, which has led some to question how the Senate considers suchnominations. (2) Duringthe Presidency of Bill Clinton and that of his successor, George W. Bush, groups in the Senate havebeen able to block confirmation of nominations, either because the nominee was never consideredby the chamber (during the Clinton presidency) or by use of the filibuster to prevent a final vote onsome nominees (during the Bush presidency). (3) The levels of frustration became very intense in the 108th and 109th Congresses, and themajority party publicly denounced its inability to end filibusters to secure votes to confirm somefederal judges. (4) To thatend, Majority Leader Bill Frist announced that he was prepared to try and change the Senate's rulesto make it easier for a majority to overcome a filibuster of a judicial nominee. First, in the 108thCongress, he introduced a resolution ( S.Res. 138 ) that would have changed theprocedure for invoking cloture, the only way to end a filibuster, by imposing an ever-decreasingthreshold for successive votes to invoke cloture on a nomination, until it could be achieved by amajority vote of the full Senate. The resolution was reported out of the Senate Rules Committee,but not considered on the Senate floor. This has been attributed to the fact that, if filibustered, atwo-thirds vote of those Senators present and voting would have been needed to invoke cloture onit. (5) On the first day of the 109th Congress, Senator Frist stated on the Senate floor that he wantedto ensure that each judicial nomination received an up or down vote by the full Senate, and he notedthat he might seek a change of Senate procedures to do this. On May 18, the Senate beganconsideration of a controversial nominee for the federal bench, and Majority Leader Frist said hewanted to obtain an up-or-down vote on that nomination, which had been previously filibustered. On May 20, a cloture petition was filed, with the vote set to occur on May 24. The media reportedthat the motion was not expected to receive the necessary 60 votes to cut off debate, and that SenatorFrist would employ a version of the "nuclear" or "constitutional" option in order to reach anup-or-down vote on the nominee. Late on May 23, however, a bipartisan group of 14 Senatorsannounced an agreement that appeared to ensure a final vote on the pending nomination and severalothers, and reduced the likelihood that the Senate would change its rules or procedures through theuse of a "constitutional" or "nuclear" option. (6) On October 31, 2005, President Bush nominated federal appellate court judge Samuel Alitoto the Supreme Court. Within hours of the announcement, there was again talk of a possiblefilibuster of his nomination, and the issue of the "nuclear" or "constitutional" option had beenrejoined. (7) Exactly because the point of a "nuclear" or "constitutional" option is to achieve changes inSenate procedure by using means that lie outside the Senate's normal rules of procedure, it wouldbe impossible to list all the different permutations such maneuvers could encompass. The following,nevertheless, represent several different approaches or scenarios that have been discussed as possiblemethods to achieve this goal. These are just a sampling of the options available to Senators; they arenot an exhaustive list. One scenario would have the effect of creating, within Senate procedure, a new precedentthat extended debate of a nomination was dilatory, and, therefore, out of order. The following is oneway such a precedent could be set. Under this scenario, a nomination would be called up and debated on the Senate floor. Aftersome time, a cloture motion to cut off debate would be filed. If the cloture motion did not get 60votes and failed, a Senator could then raise a point of order that continued debate on the nominationwould be dilatory and must end, perhaps within a specified time frame. The Presiding Officer,perhaps the Vice President, would then be expected to rule in support of the Senator's point of order. An opposing Senator would be expected to appeal the ruling of the presiding officer. Although anappeal would be debatable, it would likely be met by a non-debatable motion to table the appeal ofthe ruling of the chair. The Senate could table the motion by a simple majority vote, thusestablishing a new precedent that extended debate on a nomination can be ruled out of order asdilatory. This scenario would appear to broaden the Senate's concept of what can be considered to bedilatory. Under current Senate rules and precedents, the concept of dilatory, meaning intended todelay, has not been applied to debate by a Senator or a group of Senators. Repeated motions toascertain the presence of a quorum, for example, have been considered dilatory by the Senate, andafter the body has invoked cloture on a measure or matter, the chair has the authority to declaremotions or amendments to be dilatory, but debate has not been included in that. (8) The Senate has long considered itself a continuing body. Consistent with this premise, thepractice of the Senate has been not to re-adopt rules in a new Congress. There has been debate aboutwhether the rules that govern the Senate in one Congress should continue in effect in the nextCongress. Supporters of this position argue that, because only one-third of the membership of theSenate changes at any one time, and a quorum of the Senate is always in existence, the body doesnot need to reconstitute itself at the beginning of each Congress and, thus, the existing rules continuein effect from one Congress to the next. Opponents of this position, however, point out that underthese conditions, any change in rules must be considered under the existing rules, which can makechanging the rules extremely difficult. They contend that this "entrenchment" of the rulesunconstitutionally inhibits the Senate from exercising its constitutional authority to determine itsown rules. Those who would seek to amend Senate rules to end a filibuster by a majority vote might usethe first day of a new Congress to advance their proposal, arguing that Senate rules, particularly thecloture rule, Rule XXII, did not apply yet, and thus that debate could be ended by majority vote. Under this scenario, a Senator would move the adoption of a new rule or set of rules, which couldcontain changes to Rule XXII -- or any other rule the Senator wanted to change. Debate on the newrule or rules could be limited, subject to a majority vote, supporters argue, because the mechanicsof cloture as set out in Rule XXII would not yet apply, and the Senate would be operating undergeneral parliamentary law. Senate acceptance of these conditions would allow decisions to be madeby majority vote and could permit the use of parliamentary devices to end debate, such as calling forthe previous question, that would be decided by majority vote. (10) In order for this situationto prevail, the presiding officer would have to rule that the previously existing rules did not governconsideration of a motion to change the rules offered under these conditions, and the Senate wouldhave to endorse that ruling, most likely by tabling an appeal of the ruling, which requires a simplemajority vote to succeed. This was the situation on the opening day of the 85th Congress, on January 3, 1957, whenSenator Clinton Anderson moved to consider a new package of rules. Vice President Richard Nixon,as presiding officer, said during debate that he believed that the Senate could adopt new rules "underwhatever procedures the majority of the Senate approves." Vice President Nixon added that he didnot believe the Senate was bound by any previous rule "which denies the membership of the Senatethe power to exercise its constitutional right to make its own rules." Vice President Nixon made itclear that this was his personal opinion, not a ruling from the chair. The Senate, however, tabledSenator Anderson's motion. Senator Anderson made a similar attempt at the beginning of the 86thCongress. This time, the Senate voted to send the proposed rules changes to committee, not reachingany conclusion about changing rules on the first day. (11) In 1967, at the start of the 90th Congress, however, Senator George McGovern proposed thatthe Senate vote on a motion to consider a resolution lowering the threshold for invoking cloture. Hesaid that under the Constitution, the Senate has the right to adopt new rules by majority vote. Senator Everett Dirksen then raised a point of order that Senator McGovern's motion wouldcircumvent existing Senate rules. The presiding officer, Vice President Hubert Humphrey, ruledthat, because Senator Dirksen's point of order raised a constitutional issue, the Senate itself shouldrule on whether the point of order should be sustained. Under Senate precedents, the presidingofficer may not rule on a constitutional point of order and instead must submit the point of order tothe full Senate for a vote. (12) Humphrey also ruled that the point of order was subject to atabling motion, which was not debatable. Senator McGovern moved to table the point of order, andby a vote of 37-61 the Senate refused to table it. The Senate then voted 59-37 to sustain the pointof order. (13) In sum, Vice President Hubert Humphrey submitted the constitutional point of order to theSenate, and Senator McGovern moved to table it. The Senate failed to table, or kill, the point oforder. The Senate then voted 59-37 to sustain the point of order that Senator McGovern's motionwould circumvent existing Senate rules. With that vote, the Senate declined to allow the originalmotion to change the rules made by Senator McGovern. To employ the "nuclear" or "constitutional" option in this scenario, the Senate would haveto overturn these two precedents, perhaps among others. A variation on the first proposition would rest on a claim by proponents of changing Senaterules that on the opening day of a Congress a simple majority could invoke cloture on the motionto take up a resolution that proposed a rules change, or on the resolution itself. As in the firstopening day scenario, this action would be based on the premise that even if, in contrast to theprevious option, Senate rules were regarded as continuing in effect, the Senate must, at the start ofa new Congress in particular, be able to exercise effectively its constitutional power over its ownrules. Therefore, supporters of this approach argue, the Senate must be able to reach a vote onquestions of adopting or amending these rules. At the start of the 91st Congress (1969-1971), this approach was attempted, and the presidingofficer, Vice President Hubert Humphrey, ruled that a majority of those Senators present and votingcould invoke cloture. The question before the Senate when Humphrey made this ruling was amotion to consider a resolution to change the threshold for invoking cloture from two-thirds tothree-fifths of those present and voting. In this case, the Senator who sought to change the rules bymajority vote, Senator Frank Church, asked the presiding officer to make the determination, and theVice President then ruled. The Senate voted 51-47 to invoke cloture, and the chair ruled that themotion had succeeded by majority vote. Later the same day, the Vice President's ruling wasappealed, and the Senate voted 45-53 to overrule it, thus overturning the decision to permit majoritycloture. (14) In 1975, at the start of the 94th Congress, proponents of the proposition that a majority ofSenators could invoke cloture on a rules change at the opening of a Congress had a short-livedvictory. Senator James Pearson submitted a resolution changing the threshold for invoking cloturefrom two-thirds of those present and voting to three-fifths of those present and voting. The Senatoroffered a lengthy motion, which included as a given that a majority vote of the Senate could invokecloture on his proposal. Senator Mike Mansfield objected and raised a point of order that SenatorPearson's motion violated the rules of the Senate. The presiding officer, Vice President NelsonRockefeller, declined to rule, on the same ground cited by Vice-President Humphrey in 1967, insteadputting the question before the Senate to decide. By a vote of 51-42, the Senate agreed to a motionto table the Mansfield point of order, thus implicitly agreeing to the majority cloture proposition. Because Senator Pearson's motion was so lengthy, however, the chair ruled that it could be dividedinto individual pieces for debate. This debate occupied the Senate for several days, preventingMembers from reaching a final vote on the rules change, which could have had the effect of settlingwhether a majority could invoke cloture. (15) Less than two weeks later, the Senate reconsidered the vote by which it tabled SenatorMansfield's point of order, and then voted 53-43 to sustain it. That same day, as a part of thecompromise by which the Senate reversed itself on the point of order, Senator Robert C. Byrdoffered a series of motions that ended with the Senate adopting a change to the cloture rule, alteringthe required vote to the present standard of a three-fifths majority of those chosen and sworn (excepton propositions to change the Standing Rules). (16) Thus, the Senate briefly endorsed majority cloture, but later reversed itself and re-establishedthe precedent that the rules are continuous. Disagreements remain about whether the Senate obliterated the precedent of majority cloturewith its subsequent actions. Senator Byrd has said he believes the vote "erased the precedent." (17) Former Vice PresidentWalter Mondale, however, who was involved in the debate as a Senator, has said he believes "theRule XXII experience was significant because for the first time in history, the Vice President and aclear majority of the Senate established that the Senate may, at the beginning of a new Congress andunencumbered by the rules of previous Senates, adopt its own rules by majority vote as aconstitutional right. The last minute votes attempting to undo that precedent in no way underminethat right." (18) Successful employment of this scenario would involve the Senate overriding its later 1975decision sustaining the point of order against majority cloture, and instead reaffirming its initialimplicit decision of that year in favor of majority cloture. Another set of options for altering the requirement for cloture would involve addressing thematter not on the opening day of a new Congress, but in the course of the session. The intent of thisset of options would be to have the 60-vote threshold for cloture declared unconstitutional, either forcloture in general, or only as it applied to Senate consideration of presidential nominations, orperhaps a subset of such nominations such as of federal judges. Under Senate precedents, the presiding officer does not rule on a hypothetical situation, soit is likely that for options of this kind to be used, a nomination would have to be before the Senate,and the Senate would have to have failed to invoke cloture on the nomination. At this point, the scenario could play out in at least two different ways. It has been suggestedthat the presiding officer, probably the Vice President or the President pro tempore, could declareRule XXII unconstitutional, set the supermajority threshold aside, and rule that cloture could beinvoked by a simple majority. This ruling itself would constitute a break with Senate precedents,which, as discussed above, rely on the Senate as a whole to decide constitutional issues. If the chairissued such a ruling, opponents would likely appeal, and the appeal would ordinarily bedebatable. (19) AnotherSenator, however, could move to table the appeal, which is a non-debatable motion. If the Senatevoted to table the appeal of the ruling, a question which would be decided by a simple majority, theappeal would fail and the new precedent would appear to be confirmed, permitting cloture to beinvoked by simple majority, if the majority could get to that vote. Under a second scenario, following a vote in which the Senate failed to invoke cloture on apending measure or matter, a Senator would, from the chamber floor, make a constitutional pointof order that the supermajority requirement for cloture is unconstitutional. The presiding officermight then, in keeping with precedent, submit the constitutional question to the Senate for itsdecision. Because a procedural question submitted to the Senate traditionally is debatable, and thepoint of the exercise according to its supporters is to find a way to limit debate, however, thepresiding officer could break with precedent by ruling that the motion would not be debatable. It islikely that a Senator would appeal the decision of the chair that the question would not be debatable,and this appeal probably would be met with a counter motion to table the appeal. If the tablingmotion were successful, the appeal would fall, with the effect of sustaining the ruling of the chair. Pursuant to the ruling that the submitted point of order was not debatable, the Senate would thenproceed to vote, without debate, on the constitutional question, which would be decided by a simplemajority vote. Employment of either of these versions of the "constitutional option" would require the chairto overturn previous precedent, either by ruling on a question that by precedent has been submittedto the Senate, or by ruling non-debatable a question that by precedent has been treated as debatable. Any version of the "nuclear" option would carry with it risks and rewards. The most obviousdirect benefit would be for those judges who could be confirmed by majority vote if debate couldbe stopped by a simple majority as well. It would also strengthen the executive branch's hand in theselection of federal judges, if the Administration could be assured of confirmation with the votes of51 Senators. It also might make the Administration less likely to use its recess appointment powerto install judges on the federal bench, an issue that raised serious concerns in the Senate in2004. (20) Opponents of using any of these parliamentary maneuvers argue that the ability to confirmnominations, even those with significant opposition, by a simple majority could make anAdministration less willing to negotiate with the Senate and weaken the role of the Senate in thenomination and confirmation of presidential nominees. Furthermore, they note that the Senateconfirmed 207 of President Bush's judicial nominations and failed to confirm 10. In the 108thCongress, roughly 3% of federal judgeships were vacant at any time, not creating a significantimpediment to the operations of the federal courts, they say. (21) Supporters of using a "nuclear" or "constitutional" option to change the cloture process arguethat it could protect a Senate majority's ability to act, particularly when it came to an issue of suchvital interest as ensuring a sufficient number of federal judges to operate the courts, the third branchof the federal government. There is a serious concern among some that a constitutionalresponsibility of the Senate, to advise and consent to presidential nominations, is being weakenedwith the repeated, successful filibusters of certain federal judicial nominations. (22) Because the Senate has not utilized the "nuclear" or "constitutional" option before, theconsequences of doing so are unclear. The potential exists for significant repercussions. Indescribing the Senate, most modern congressional scholars now refer to it as a "unanimous consentbody." By far the greatest share of the chamber's business is conducted, one way or another, byagreement among all Senators. In part, the reason is that Senators have learned to agree on how toproceed, knowing that such procedural agreement does not necessarily predetermine the outcomeof policy decisions. The use of a plan which would intentionally use a procedural tool to force afinal decision on a policy option could make it dramatically more difficult to obtain unanimousconsent for anything else that followed. Both sides of the debate seem to be concerned about the possible results. In the opinion ofone Democratic Senator, the use of the "nuclear" option "â¦ would be a dagger at the heart of whatthe Senate is all about, and Democrats would take very strong action." (23) A Republican Senator told The Hill that damage from the use of the "nuclear" or "constitutional" option could level the Senate,making it very difficult for work to get done. "The nuclear option on judges, it rather clears thelandscape," the Senator said. (24) The procedural maneuver also could change the nature of the Senate, in which it is difficultto override the rights of the minority. It would raise fundamental and significant questions abouthow the institution would function, the answers to which would become clear only as time passed. If the power of the filibuster were broken, for example, would the Senate become more like theHouse of Representatives, in which debate and deliberation can be terminated at the option of themajority? Or would it become a chaotic environment in which a temporary majority could changeprecedents any time it wanted to? Another concern would be consequences for other rules of the Senate. Because it is sodifficult to change the Senate's rules, they have remained fairly stable, and therefore the basicstructure of Senate procedure has remained fairly constant. If, however, a change to the rules wereaccomplished by a majority vote, nothing would prevent other changes to the rules from beingproposed, which could then conceivably be accomplished with a majority vote to end debate on themas well. In addition, even if a "constitutional" or "nuclear" option were used, opponents still mightbe able to delay a final vote on whatever measure or matter was pending. Existing Senate precedentswould seem to allow an endless series of amendments to a proposed rules change, even if no debatewere allowed. The Senate routinely does this each year when it considers the annual budgetresolution. Therefore, it is unclear that the "constitutional" or "nuclear" option by itself could bringabout a vote on a rule change. Further, even if the use of this option resulted in a lower cloture votethreshold, other portions of the rule would presumably remain untouched, in which case thepost-cloture process still would provide delaying possibilities for opponents. Additional questions arise if the Senate used an opening day gambit. Would successfulaction in this form change the understanding of the Senate as a continuing body? Would this changemean that the Senate would have to elect its officers and adopt its rules at the start of each Congress? One potential alternative would be to modify other Senate practices (instead of changing thecloture rule) or to enforce existing Senate rules more stringently. A number of possible approachescould be used to bring debate to a close absent any formal change to Rule XXII. For example, the Two-Speech Rule does not apply to executive business in the same way itdoes to legislative business. Limiting senators to two speeches during the consideration of anynomination, regardless of how many session days the nomination was pending, would bring abouta vote on a nomination without the need to invoke cloture, or to consider amendments to the cloturerule. Another alternative might be to require Senators who wish to filibuster a measure or matter(such as a nomination) to hold the floor and talk to maintain their filibuster. In the modern Senate,such displays are rare. Instead, the Senate routinely permits Senators to "suggest the absence of aquorum" as a means to delay action without the need to debate. The Senate, by precedent, has ruledsuch quorum calls dilatory, after cloture. By precedent, the Senate could make such quorum callsdilatory at any time, if no substantive business had intervened since a quorum had been previouslyestablished. The two-track system allows other business to come before the Senate even as the pendingbusiness remains unresolved. As a result, time on the Senate floor is more often used to conductbusiness on which there has already been agreement, rather than to debate or amend measures, orfilibuster them. Removing a contentious measure from active consideration allows the threat of afilibuster to halt a measure, instead of requiring opposition Senators to openly debate the measureand explain their concerns publicly. The Senate no longer relies on extended continuous session to put pressure on oppositionSenators. Such late-night or multiple day sessions were common until a generation ago. The disuseof a traditionally effective strategy to end debate or to encourage policy compromise has led, in theopinion of some, to the consideration of ill-advised rule changes when less drastic changes to Senatetradition could achieve the desired result. (25) 

Summary: Reports indicate possible attempts to curtail the use of filibusters in the Senate, perhaps inthe 109th Congress. Some have suggested that proponents of this idea may invoke something calledthe "nuclear" or "constitutional" option in Senate floor procedure to try to end a filibuster withoutthe need for 60 votes or to amend the cloture rule (Rule XXII) itself. No set definition exists for theterm "nuclear" or "constitutional" in this context. Because the point of using such an option is toachieve a goal by means lying outside the Senate's normal rules of procedure, it would be impossibleto list all the different permutations such maneuvers could encompass. Several likely scenarios thatfall into this category are described in this report, followed by a discussion of the possible advantagesand disadvantages of using such an approach. Opponents (and some supporters) of this kind of plan typically refer to it as the "nuclear"option because of the potentially significant result for Senate operations that could follow from itsuse. The Senate relies heavily on unanimous consent to get its legislative work accomplished. Itmay be more difficult to achieve unanimous consent in an environment where the minority feels ithas lost some of its traditional rights. Supporters of the concept of majority cloture argue that it isa "constitutional" option because they will be making their argument based on a constitutionalprerogative or duty of the Senate. One method for changing Senate procedures might involve declaring extended debate onnominations dilatory, and thus, out of order. Another possibility is based on the argument that, onthe first day of a new Congress, Senate rules, including Rule XXII, the cloture rule, do not yet apply,and thus can be changed by majority vote. Under this argument, debate could be stopped by majorityvote. A Senator would move the adoption of a new rule or set of rules. The new rule or rules wouldbe subject to a majority vote, supporters argue, because the mechanics of cloture as set out in RuleXXII, which requires a supermajority to invoke cloture and end debate, would not yet apply and theSenate would be operating under general parliamentary law. One variation would be a claim thaton the opening day of a Congress a simple majority could invoke cloture on the motion to take upa resolution that proposed a rules change, or on the resolution itself. Again, this scenario would reston the proposition that Rule XXII was not yet in force and did not control action. Senators alsocould seek to have the 60-vote threshold declared unconstitutional, either for cloture in general, oronly as it applies to Senate consideration of presidential nominations, or perhaps a subset of suchnominations, such as of federal judges. This scenario might take place in at least two different ways. The presiding officer might make a ruling from the chair, or a Senator could make a point of orderfrom the floor that the supermajority requirement for cloture is unconstitutional. All these possible scenarios would require that one or more of the Senate's precedents beoverturned or interpreted otherwise than in the past. This report will be updated as events warrant.