If you can't manage the 60 votes to overcome a filibuster, you can't manage the 67 votes to change the rules and end the filibuster. At least in theory.
But in practice, there's another path open to the Senate's growing ranks of reformers: The so-called "constitutional option," which is being pushed particularly hard by Sen. Tom Udall, but is increasingly being seen as a viable path forward by his colleagues.
The constitutional option gets its name from Article I, Section V of the Constitution, which states that "Each House may determine the Rules of its Proceedings." In order to fulfill this constitutional order, the Senate must be able to, well, determine its rules. A filibuster, technically, is a way to stop the Senate from determining something by refusing to allow it to move to a vote. Because stopping the Senate from considering its own rules would be unconstitutional, the chair can rule against the filibuster, and the Senate could then move to change its rules on a majority vote.
One caveat: Many people, including Udall himself, believe this has to happen at the beginning of a new Congress. If it doesn't happen at the beginning of a new Congress, then Congress is considered to have acquiesced to the previous Congress's rules, and a filibuster against further rule changes wouldn't interrupt the constitutional right to determine the rules.
This is not a radical theory, or a partisan one: Both Richard Nixon, then the vice president and thus the president of the Senate, and Robert Byrd, then majority leader and considered the greatest parliamentarian to ever walk the chamber, have argued in favor of the constitutional option.
Martin Gold recounted Nixon's argument in a 2004 article for the Harvard Law Review: "Nixon reasoned that because no Senate could deny a future Senate the ability to exercise a constitutional right, and because Rule XXII, paragraph three [the filibuster] "in practice" prevented a majority of Senators from adopting new rules, Rule XXII, paragraph three, was unconstitutional," at least when it came to blocking consideration of new rules. Byrd was even pithier: "This Congress is not obliged to be bound by the dead hand of the past," he said.
But for all the theory, the constitutional option has never quite been used in practice. Instead, it's been repeatedly, and effectively, almost used. In 1917, Senate reformers were ready to use against the filibuster. A compromise was brokered, and that's how cloture -- the ability to shut off a filibuster -- was created. In 1975, reformers again were ready to wield it against the filibuster, and this time, a motion to uphold the constitutional option passed and a motion to table it failed. And again, a compromise was brokered, this time bringing the number of votes necessary to breach the filibuster down from two-thirds of the Senate to three-fifths. The option was also considered for various reasons in 1953, 1957, 1961, 1963, 1967, 1969, 1971, and 1979.
And that gets to the real role that the constitutional option could play: If Democrats lay out a clear path to changing the rules through a majority vote, and if they show enough unity to convince Republicans that they'll really try it, you might see a hasty decision to reach some sort of bipartisan compromise on the rules. But if Democrats push this strategy only to find themselves unable to follow through on it, they may find that they've lost their ability to protest rules changes if Republicans decide to pursue the same strategy when they eventually retake the Senate.
