Donald J. Trump can be brilliant. On the campaign trail, his diagnosis of the raw anger and disillusionment among white working-class Americans bested the most sophisticated analyses from the professional political class.

His description of “American carnage” in his Inaugural Address — complete with “rusted-out factories scattered like tombstones across the landscape,” impoverished mothers and children, crime, drugs that “robbed our country of so much unrealized potential” — struck a nerve with millions of voters who feel left behind by a country buffeted by demographic, technological and social change.

But something must have happened between then and now.

President Trump cannot possibly believe that nixing the health insurance of 24 million poor or nearly poor Americans to pay for tax cuts at the very top of the income distribution would serve the white Everyman he promised to defend.

It’s also hard to fathom how whites without a college degree would benefit from Mr. Trump’s proposal to cut $54 billion from the civilian discretionary budget — slashing projects to help low-income families pay for heating in the winter or move to better neighborhoods; cutting nutrition assistance for mothers and help for low-income students to enter college.