With the Democrats promising to block the nomination of Judge Neil Gorsuch for a seat on the U.S. Supreme Court, many expect Senate Majority Leader Mitch McConnell to use the so-called nuclear option to lower the number of votes needed to end debate. This actually happened before, in November 2013, when then Senate Majority Leader Harry Reid invoked the nuclear option to end debate on most nominations (except for those for the Supreme Court) by only a simple majority. Based on the last time the nuclear option was used, here’s a somewhat simplified version what this arcane process may look like (although the exact details could vary).

For starters, let’s make a couple important definitions and distinctions about filibusters, rules, precedents, and cloture. For this we’ll rely on one of our old blog posts:

There are three ways the Senate governs itself: 1) the Standing Rules, first passed in 1794 and amended from time to time; 2) Standing Orders, such as unanimous consent agreements made to regulate how debates will be conducted and other orders passed by the Senate; and 3) the precedents of the Senate, which determine how a standing rule will be interpreted without changing its text. From time to time, parliamentary procedure has collided with partisan politics to stop the Senate. Now is such a time, and now as ever, Senators eager to legislate have tried to find a way to change the rules to expedite the process.

The Standing Rules of the Senate permit filibusters. This is a tactic that an opponent of a bill uses to delay it or kill it off entirely. The present problem with the filibuster is that it has become the de facto starting point for debate on the Floor of the Senate. Filibusters, however, may be ended by cloture, which cuts off debate and requires an eventual vote on the question at hand. The Senate’s Rule XXII governs cloture. Since 1975, to invoke cloture, 16 Senators must file a petition. After two days the Senate votes on the cloture motion. If it passes, there are 30 more hours of debate before the vote must be called. During the 30-hour debate, amendments must be germane and each Senator is limited to an hour of debate. To pass, a cloture vote on a normal measure must receive three-fifths of the Senate (60 votes). The high bar to break a filibuster frustrates each party when it is in control, and now the majority tries to find ever-more creative ways to try to force a change in the rules.

The nuclear option exploits the differences between the Standing Rules and precedents. To change how one of the Standing Rules is written, the Senate must develop a wide consensus, because the threshold for a successful cloture vote is so high for resolutions amending the rules. Precedents are set when the Senate upholds a ruling of the Presiding Officer or when it overturns the ruling of the Presiding Officer. The Senate needs only to garner a simple majority to uphold or overrule the Chair’s decision.

Senator McConnell has already set the stage for the nuclear option by submitting a cloture petition. On Thursday, Senator McConnell’s cloture petition will “ripen,” meaning it will be eligible for a vote. Rule XXII clearly states that “three-fifths of the Senators duly chosen and sworn” are required to cut off debate (except if the business be a change to the rules, in which case “two-thirds of the Senators present and voting” are required). If there are no vacancies, three-fifths of the Senate is 60 votes. Only four Democrats have said they would vote for cloture, so the cloture motion will fail.

Here comes the radioactive part. Although the cloture vote fails, the Majority Leader could move to reconsider—i.e., revote—and make a point of order that only a simple majority is required for a successful cloture vote. The Presiding Officer, whether it is the Vice President of the United States or the Senate President Pro Tempore, will overrule him, since Rule XXII clearly states that a supermajority is required. Then the Majority Leader can appeal the decision to the whole Senate. The Presiding Officer will ask the Senate, “Shall the decision of the Chair stand as the judgement of the Senate?” If a simple majority answers “nay,” then the Presiding Officer will be overruled and the Senate precedent will be that cloture requires a simple majority. The Presiding Officer would then announce the new ruling and this precedent would be used to govern future cloture votes.

Throughout this process, several other parliamentary maneuvers might be attempted. For instance, the Senate Democratic Leader Chuck Schumer might try to delay the proceedings by moving to adjourn or making parliamentary inquiries. After the Presiding Officer announces that the ruling of the Chair is that cloture requires only a simple majority, Senator Schumer could appeal this decision to the whole Senate as well. However, the result of this vote would be the opposite of the first vote to overrule the Chair. The Republicans would vote “yea, ” and the Democrats would vote “nay.” This time, the Presiding Officer’s decision would stand.

One variable is how far the new precedent will extend. When Senator Reid set off the nuclear option in November 2013, his point of order was specific: “I raise a point of order that the vote on cloture under rule XXII for all nominations other than for the Supreme Court of the United States is by majority vote.” The text of rule XXII nowhere says that cloture is by simple majority vote, nor does it carve out any special exceptions for the Supreme Court. In other words, Senator Reid crafted his point of order to suit his needs. Senator McConnell could well do the same. In fact, he could go so far as to lower the threshold for cloture for legislation and the Senate’s Standing Rules. However, Senator McConnell has stated that the Senate Republicans don’t wish to weaken the legislative filibuster, so any new precedent will probably be more narrowly crafted.

The forgoing suggests that, when armed with the nuclear option, there seems to be little that a Majority Leader cannot do if he can muster 51 votes in favor of some action. This makes the Senate a much more majoritarian institution, where the party in power can easily do what it likes, when it likes, and how it likes. Each party can find a lot to like in that arrangement—today, conservatives will cheer Gorsuch’s confirmation—but it also means they lose vital powers to shape or stop Senate business when they are in the minority. Will that tradeoff be worth it? More importantly, what rule will change next?