While watching the race for the Republican presidential nomination unfold, it’s hard not to wonder – on a nearly daily basis – whether the slow-rolling fiasco could possibly get any worse.

And then it gets worse.

The setup for last night’s debate in Michigan actually began late last week , when Marco Rubio decided it’d be politically smart to attack Donald Trump’s hair, face, skin tone, and sweat. The Florida senator added that Trump might urinate on himself, before saying in reference to his rival, “And you know what they say about guys with small hands.”

In their first debate since Rubio’s race to the gutter, Trump decided to respond in last night’s forum. From the transcript

“I have to say this, I have to say this. [Rubio] hit my hands. Nobody has ever hit my hands. I have never heard of this. Look at those hands. Are they small hands? “And he referred to my hands, if they are small, something else must be small. I guarantee you there is no problem. I guarantee.”

Yes, for the first time in the history of the United States, Americans witnessed a debate for presidential candidates in which a major-party frontrunner made a not-so-subtle reference to the size of his genitals. To this extent, it was a debate that made history – but not in a good way.

Ordinarily, in the context of campaign politics, when we say “size matters,” we’re talking about delegate counts, fundraising and poll advantages, or perhaps attendance at rallies. But in 2016, as Republican politics unravels, the phrase has somehow taken on a far cruder meaning.

What’s more, Trump’s manhood boast came fairly early on in the debate. When a forum for presidential candidates includes a penis reference in the first 10 minutes, really, it’s awfully difficult to recover. Once the tone is established, it’s practically impossible to raise the level of an event’s discourse to something approaching “presidential.”

After any debate, the political chatter quickly shifts to who “won” and “lost.” After a debate like this one, it’s a fairly easy question to answer: Hillary Clinton won and the Republican Party lost.

I n nominal terms, we can draw traditional assessments. Trump was targeted aggressively by his rivals and the moderators, and struggled to withstand the pressure. Rubio seemed childish and nervous. Ted Cruz did a decent job of being an adult while taking a few effective shots at the frontrunner. John Kasich impressed everyone except Republican primary voters.

But to appreciate the forest instead of the trees, the debate served as a reminder of Trump’s dominance, not only over the GOP field, but in changing the direction of the party’s politics at a fundamental level.

TPM’s Josh Marshall noted overnight, “You may have noticed that during the debate audience members in the line of sight behind the moderators were giving thumbs ups, making faces or just aping for the cameras like you’d expect to see at a football game or a wrestling match. We’ve never seen anything like that. The pro-wrestling mania of the Trump rallies is seeping into debates, like a virus spreading through a host body. And I tend to doubt that those people were all Trump supporters. It doesn’t matter. Creeping Trumpism is taking over his opponents from within.”

Quite right. These cringe-worthy gatherings are increasingly centered around – literally and figuratively – the offensive showman who’s leading the race, and who’s gradually remaking the party in his own image.

For the Republican Party as an institution, that’s a tragedy without modern parallel. Jamie Johnson, a former aide to Rick Perry’s defunct presidential campaign, said last night , “My party is committing suicide on national television.”