Mitch McConnell had a warning for Democrats in a New York Times op-ed on Thursday: Eliminate the filibuster at your peril.

“Yes, the Senate’s design makes it difficult for one party to enact sweeping legislation on its own. Yes, the filibuster makes policy less likely to seesaw wildly with every election,” the Senate majority leader writes. “These are features, not bugs.”

McConnell’s post, of course, underlines an interesting paradox: Even as he calls for the preservation of a longstanding Senate rule, he glosses over the fact that he’s blown up many of the upper chamber’s norms himself.

His message comes as Democrats on the 2020 campaign trail ramp up their talk of getting rid of the filibuster for good, a structural reform that would reshape Senate dynamics and that many see as increasingly necessary in order to push ambitious, progressive legislation through Congress. It also follows an August New York Times op-ed from retired Democratic Senate Majority Leader Harry Reid, who argued that the filibuster was single-handedly responsible for obstructing vital policy on gun control and immigration.

The idea of eliminating the filibuster — congressional procedure that effectively sets a 60-vote threshold for any legislation to pass the Senate — has gotten mixed reviews from 2020 candidates. But it has picked up momentum as a campaign talking point, largely because many Democratic plans, including Medicare-for-all and the Green New Deal, would have little chance of passage if it remained.

McConnell’s case for preserving it is yet another instance of the majority leader actively trolling Democrats: He’s arguing for the sanctity of Senate rules after he’s disregarded many of them himself. It’s also a sign, potentially, of McConnell seeing the need to go on the offensive as the Democratic push for retaking the upper chamber in 2020 heats up.

McConnell’s case against the filibuster glosses over Republican obstruction

McConnell lays out a case for preserving the filibuster by arguing that the Senate, unlike the House, was designed to be the deliberative body of Congress, which has also been described as the “cooling saucer” for ideas. Effectively this means that the Senate is a place where legislation gets approved much, much slower, if at all.

Historically, this dynamic has translated to a wholesale stymying of legislation on civil rights, environmental protections, and immigration, all of which have died in the Senate because they weren’t able to garner enough Republican support. Because of how much this Senate procedure has thwarted civil rights legislation including bills that would make lynching a federal crime, lawmakers including Sen. Elizabeth Warren argue that it’s helped fuel racism, among other critiques.

McConnell warns that Democrats would regret their decision to do away with the filibuster in the same way that certain lawmakers have expressed concern about their decision to get rid of a filibuster on judicial nominees, a rule that previously set up a 60-vote threshold for their confirmation. Reid first championed this move in 2013, and since then, Republicans have regained power in the Senate and capitalized on this change in order to advance judges at a breakneck pace.

McConnell emphasizes that Democrats could certainly use changes to the filibuster to promote what he calls “socialist” policies, but emphasizes that Republicans would one day be able to use them as well:

Senate Democrats bought what Senator Reid was selling — but buyer’s remorse arrived with lightning speed. Just one year later, Republicans retook the majority. Two years after that, Americans elected President Trump. In 2017, we took the Reid precedent to its logical conclusion, covering all nominations up to and including the Supreme Court.

There’s a strong degree of irony to McConnell’s arguments: Even as he’s pushing for Democrats to keep the filibuster in the name of preserving Senate rules and tradition, he’s personally done significant damage to congressional norms.

As McConnell notes, Democrats were the first to change the filibuster rules on judicial nominees. What he doesn’t say, however, is that the reason Reid felt compelled to do so because McConnell had mounted an overwhelming obstruction of non-controversial judicial nominees. And that’s far from the only time McConnell has levied his power as majority leader to reject Senate norms.

When President Barack Obama’s Supreme Court nominee Merrick Garland was up for confirmation, McConnell didn’t even hold a hearing. Earlier this year, McConnell pushed through another rules change on judicial nominees, enabling lawmakers to confirm judges even faster. This congressional term, he has become known for blocking consideration of countless House bills, including on the topic of election security, declaring himself the “grim reaper” of Democratic legislation on Capitol Hill.

Even if Democrats retake the Senate, there’s no guarantee they’d end the filibuster

McConnell’s op-ed was published as the fields for battleground Senate seats are starting to take shape, with former Colorado Gov. John Hickenlooper most recently announcing that he’ll pursue the state’s seat. As Vox’s Tara Golshan and Ella Nilsen explained, Democrats still have a pretty tough challenge if they want to retake the upper chamber. But as more candidates declare in places like Maine and North Carolina, they’re beginning to build out their opposition.

If Democrats were able to flip the Senate, eliminating the filibuster could certainly be within their reach. Senate Minority Leader Chuck Schumer has not ruled out the possibility, and he’d likely be on the spot if Democrats were in a position of power.

At the moment, Democrats aren’t exactly united in how they’d take on this issue, either. While several leading 2020 candidates including Warren and Rep. Seth Moulton have come out forcefully in favor of killing the filibuster, others, including Sen. Cory Booker and Kamala Harris, have been more circumspect. As Vox’s Matt Yglesias explains, the filibuster doesn’t just block major legislation — it’s also given lawmakers some political cover on difficult votes:

A senator can even take a position in favor of some sweeping piece of legislation and then quietly reassure interest group opponents that everyone knows this isn’t getting 60 votes and really just represents an opening bid. Senators in purple states, meanwhile, often enjoy the ability to avoid taking clear positions on issues. Since many areas of policy can, in practice, only be legislated on via bipartisan deals, it’s usually possible for a member to remain ambiguous whenever that seems most suitable.

Per Reid’s previous op-ed, however, Democrats’ need to advance the legislation they want may outweigh their reservations about changing the Senate rules for good. “If the Senate cannot address the most important issues of our time, then it is time for the chamber itself to change, as it has done in the past,” Reid wrote.