In the House, before a bill can be voted on, members adopt a measure to establish ground rules for how the legislation will be considered. It’s known as adopting a “rule,” and the vast majority of the time it’s little more than a procedural speed bump, because members tend to vote with their parties to begin the process.

During Democratic Rep. Nancy Pelosi’s tenure as House speaker, she literally never lost a rule vote. During former Republican Reps. John Boehner’s and Paul Ryan’s tenures, they also never lost such a vote.

In the last Congress, however, then-Speaker Kevin McCarthy lost three of these votes. And after he was stripped of his gavel, his Republican successor, Mike Johnson, lost four.

In the current Congress, Johnson lost one rule vote last year, and then another Tuesday night. This latest failure, however, was almost certainly the most important to date. MS NOW reported on what happened when House GOP leaders tried to adopt legislation Tuesday night that would prevent any lawmaker from forcing a vote on Donald Trump’s tariffs until August:

That effort failed, however, 214-217, after three Republicans joined all Democrats to defeat the legislation.

Tucked into a rule setting up floor consideration for a bill on U.S. energy security was language that would have prevented House lawmakers from challenging Trump’s tariffs until July 31. The language stipulates that certain days won’t ‘constitute a calendar day’ for the purpose of terminating national emergencies — the authority Trump has used to impose the tariffs.

The procedural details get a little complicated — the goal, as The New York Times summarized, was to “manipulate the laws of time … turning months into a single legislative day” — but what matters more is the broader significance. Indeed, Politico described Tuesday night’s developments as “seismic,” and it’s worth appreciating why.

First, this was a major setback for Trump, who expected the House chamber that he has effectively controlled for a year to back him up on his controversial trade tariffs agenda. When that didn’t happen, it offered fresh evidence of an unpopular lame-duck president whose grip on Capitol Hill, even when his own party is in control, is clearly loosening.

Second, this clearly didn’t do the House speaker any favors. Johnson, who has long been seen as a weak figure, has now lost more rule votes than any speaker in generations, and the Louisiana representative’s troubles are only going to get worse. In the wake of Tuesday night’s failure, Democrats will be able to force a series of uncomfortable votes on the White House’s tariffs, and GOP leaders, already struggling with a vanishingly small majority, won’t be able to stop them.

“As the midterms get closer, Democrats will use these votes as a cudgel against vulnerable Republicans,” Punchbowl News summarized.

And third, this was a fundamental rejection of an entire partisan mindset. Johnson’s goal was, at its core, bizarre: Tuesday night’s vote was intended to neuter his own chamber in order to prevent votes against tariffs that Congress is supposed to have authority over, but which the House speaker wants Trump to use unilaterally.

In effect, Johnson told House members to keep surrendering their own legal authority so that the president can continue to use tariffs in ways most Americans oppose.

Then most House members replied “no,” adding to the speaker’s list of embarrassments.