It was neither the #TrumpShutdown nor the #SchumerShutdown. It wasn’t even the #StephenMillerShutdown.

It was always the #McConnellRyanShutdown.

Senate Majority Leader Mitch McConnell and House Speaker Paul Ryan are responsible for the completely avoidable three-day federal shutdown that ended Monday. They will likewise be responsible for the catastrophe coming in a few weeks if Congress can’t get its act together to raise the debt ceiling.

McConnell and Ryan, after all, not only lead the majority party. They also control the legislative agenda. They determine which bills come up for a vote and when. And they knew far in advance the drop-dead deadlines for keeping the government funded.

They also knew the Democrats’ conditions for cooperating.

But McConnell and Ryan chose to do nothing. Worse than nothing: They frittered away their precious time and political capital on policy pursuits that were totally irrelevant. Worse than totally irrelevant: actively destructive.

Every year, Congress must pass a budget. This is … not a surprise. Yet for the first half of last year, Republican congressional leaders chose to spend their time and energy chasing a repeal of Obamacare, a phenomenally unpopular endeavor that would have raised premiums and ripped health insurance from tens of millions of Americans.

They failed, of course. In the meantime, they also missed their opportunity to pass a budget before the new fiscal year began in October.

So they kicked that can down the road, passed a stopgap funding measure and promised to deal with a real budget later. Sometime before early December.

Instead of even attempting to pass a budget at that point, Ryan and McConnell pivoted to another unrelated, unpopular and fiscally profligate hobby horse: tax cuts for corporations and the rich.

This time they were successful. But while they futzed around with the Obamacare repeal and $1.5 trillion in plutocratic tax cuts, more time-sensitive crises accumulated.

Some, such as the hurricanes that devastated Puerto Rico, were natural. Others were man-made: Authorization for the Children’s Health Insurance Program lapsed, leaving 9 million low-income kids in limbo. And with McConnell and Ryan’s blessing, President Trump announced that undocumented immigrants brought here as children would be subject to deportation come March, unless Congress acted.

No matter. The only thing McConnell and Ryan felt any urgency to work on was stuff their donors care about. They focused on that and orchestrated more stopgap budgetary measures in their spare time. Monday’s, in fact, represents the fourth stopgap 2018 funding bill, with this one set to expire on Feb. 8. It does, at least, include a six-year reauthorization of CHIP.

Don’t get me wrong. Trump has not exactly been helpful in brokering a deal on budgets, health care, immigration or other major policy issues. When he has gotten involved, he’s often struggled to remember what’s existing law, what his own positions are and how the legislative process even works.

McConnell and Ryan have no such excuse. Collectively, they have served five decades in Congress. They know Congress’ arcane procedures and obligations and, again, they set the agenda. To date, that agenda has not included a single serious budget deal.

Somehow this dynamic duo still takes no responsibility for our lack of a budget. They’re like students who play video games instead of writing their term paper, plead for extensions, still wait until the last minute to start writing — and then blame the teacher when they don’t finish.

As embarrassing as this shutdown was (and as embarrassing as another one will be if there’s no budget agreement by Feb. 8), shutdowns are not catastrophic. Far more worrisome is what McConnell and Ryan’s abdication of leadership means for another showdown rapidly approaching.

Because, unfortunately, the budget isn’t the only basic responsibility they’ve been shirking. There’s also the matter of safeguarding the validity of the public debt, a constitutional requirement.

Rather than substantially raising (or, better yet, eliminating) the statutory debt limit, Congress has likewise relied on a series of stopgap measures for paying our creditors over the past year. The Treasury Department has had to resort to “extraordinary” accounting measures to stave off a debt default, which could trigger a worldwide financial crisis.

The latest round of such measures, which began in early December, will likely be exhausted sometime in the next several weeks. Meanwhile, the markets look nervous.

Yet instead of laying the groundwork now to prevent default, McConnell and Ryan engage in hashtag wars. They’re cutting more taxes. Ryan is even fantasizing about slashing entitlements.

#McConnellRyanShutdown is bad enough. Let’s hope #McConnellRyanCrash isn’t next.

Catherine Rampell