Mitt Romney’s vicious dismantling of Donald Trump—as a candidate, as a businessman, and as a human being—marks a turning point in the modern history of the Republican party. It could well become the moment an irreparable chasm opened between the GOP’s old guard leadership and the angry electorate propelling Trump’s candidacy toward the nomination — a split that rips the party in two.

And if that’s the case, Romney’s Thursday speech will be studied for a long time to come for the forensic evidence it offers about how this fracture came to pass.

One of the more quietly remarkable aspects of the address was what it didn’t say. Romney offered Trump no credit for effectively articulating the interests of the voters he’s capturing. Instead, Romney said Trump is “playing the members of the American public for suckers.” That’s a short hop from demeaning as rubes the hundreds of thousands who’ve already cast votes for the Republican frontrunner.

Strafing Trump’s economic program, Romney called him out for threatening to start trade wars, refusing to trim entitlements, and not seriously addressing government spending. More than a few Trump supporters tuning in likely thought, “Exactly.”

Whatever you think of Trump’s solutions, those forming the core of his support have a coherent set of concerns that his platform, such as it is, takes on. It revolves around a brand of economic nationalism that emphasizes the needs of increasingly insecure, largely white, working class voters. These people share nothing of the party elites’ concern for spending in the abstract and, in fact, want their share of entitlements. They’re deeply suspicious of any trade deals, and they view unchecked illegal immigration as a direct threat, putting them in opposition to the party’s free-market orthodoxy on those defining issues as well.

The Republican leadership class is now frantically trying to pry what it can of the party away from what Trump’s already seized. In doing so, Romney and others can ignore the gulf between their own consensus and the priorities of the conservative base by dismissing Trump as a conman and a clown. Indeed, Trump himself has made that easy by placing his reality-show persona so squarely at the center of his bid. But writing his supporters off similarly will only complicate the task of mending what’s tearing the party apart.