I loathe the filibuster. Really. It's right there in my Twitter bio. But a few years ago, loathing the filibuster seemed a quixotic crusade. The right and the left seemed broadly united behind it. Challenges to the filibuster — like the one Republicans mounted in 2005 over judicial filibusters — seemed to inevitably end in the Senate's traditionalists banding together to protect the Senate's treasured tendency toward paralysis and dysfunction.

But not anymore.

In 2013, Democrats weakened the filibuster with 51 votes. The actual change to the filibuster was modest — they made most nominations exempt from the filibuster but left the 60-vote threshold unchanged everywhere else. But the precedent was profound. There's often been debate over whether you need a simple majority or a two-thirds supermajority to change the filibuster rule. Democrats proved it only requires a simple majority. So the Senate's 60-vote threshold exists at the pleasure of 51 senators.

The importance of this could hardly be overstated: the filibuster rests on an unstable foundation.

Since then, the erosion of support for the filibuster has proceeded quicker than I could have hoped. Democrats had clearly begun to polarize against the practice — hence the 2013 change. But it wasn't only Senate Democrats who had begun to doubt the rule's worth. In his interview with Vox, President Obama, who had strongly defended the filibuster from Republican efforts to weaken it in 2005, called for "the elimination of the routine use of the filibuster in the Senate." He continued:

In an era in which the parties are more polarized, it almost ensures greater gridlock and less clarity in terms of the positions of the parties. There's nothing in the Constitution that requires it. The framers were pretty good about designing a House, a Senate, two years versus six-year terms, every state getting two senators. There were a whole bunch of things in there to assure that a majority didn't just run rampant. The filibuster in this modern age probably just torques it too far in the direction of a majority party not being able to govern effectively and move forward its platform.

Obama is right about this, incidentally. The filibuster is a poor fit for an era with highly polarized parties. It's one thing to have a rule that allows individual senators or small groups of senators to stop the Senate and force more debate over issues of extraordinary importance. But with polarized parties engaged in organized procedural warfare, the filibuster has become something else entirely: a way not for minorities to be heard, but for majorities to be stymied. It becomes, as Obama said, routine, when for most of American history it was extraordinary.

Today's filibuster rarely has anything to do with debate at all: no one stands on the floor of the Senate and talks till they drop. Filibusters are pure procedure, a way to move the Senate from majority rules to supermajority rules. That's the key to understanding the filibuster debate: American politics changed, and that changed the role the filibuster plays in the Senate.

So Democrats — including the sitting president of the United States — are turning on the filibuster. But perhaps that's to be expected. They're the party that's been most stymied by it in recent years.

What's been surprising is how fast Republicans are turning on it, too.

Republicans are turning against the filibuster, too

When the GOP took back the Senate, there was speculation that they would restore the filibuster to its former power. They didn't. Instead, two members of the leadership — Sens. Lamar Alexander and Mike Lee — proposed to weaken it further by exempting Supreme Court nominees, too.

Among the party's intellectual leaders, the move against the filibuster is growing yet stronger. "Abolish the filibuster," conservative columnist Charles Krauthammer wrote. He continued: "I know that breaks a lot of china. But Congress is already knee-deep in fractured porcelain."

In Tuesday's Wall Street Journal, Republican lawyers David Rivkin and Lee Casey have an op-ed titled, "To Stop Obama's Power Grabs, Kill the Senate Filibuster." They argue:

It is important to understand that the Senate filibuster rule has no constitutional basis. That document does not reference a "filibuster," but merely permits each house of Congress to determine its own procedural rules. The filibuster is a historical fluke, resulting from the Senate's failure to impose constraints on how long senators may speak on a particular matter, thereby delaying other business and especially votes on legislation that require only a majority to pass. Only a cloture motion, which requires a supermajority of three-fifths (60) to pass, can end these delaying tactics-and cloture has become nearly impossible to achieve because of an increasingly ideologically divided Senate in which neither party has a supermajority. This raises fundamental issues: Since all constitutional provisions must be read in harmony, rules in one house that consistently frustrate the ordinary legislative process by preventing a vote work to nullify other key congressional powers. Ultimately, this undermines the Constitution's balance of power between Congress and the executive.

Even worse for the filibuster, both sides are completely convinced that if they don't eliminate the filibuster, the other party will do so as soon as it's convenient. "There is every reason to expect that similar political expediency will lead to future limitations on the filibuster when there is again a Democratic Senate majority — which should give comfort to any Republicans who continue to support the filibuster out of respect for Senate tradition," write Rivkin and Casey.

A few years ago, I thought it basically impossible to imagine the filibuster would be eliminated or seriously curtailed in the near future. Now, it's increasingly hard for me to imagine how it won't be.