Wipe that smile off your face, Mitch McConnell. Photo: Chip Somodevilla/Getty Images

Of all the horrors Donald Trump has (and has yet to) inflict upon the republic, a huge tax cut for the rich was the most inevitable. But it is also the most easily reversible. Lifetime court appointments, carbon pollution, the degrading of democratic norms — all of these will prove difficult or impossible to undo, and leave costs deep into the future. The Trump tax cuts will not.

Indeed, the passage of the Trump tax cuts will help lay the groundwork for their undoing by increasing the chances Democrats regain control of Congress. The moment Trump won his election last November, he immediately forfeited his most potent advantages: He no longer had the deeply unpopular Hillary Clinton as his opponent, and he lost the advantage of Democratic complacency (which tends to build up over time when their party holds the White House). An anti-Republican wave of some size was always inevitable. But Trump compounded the problem by surrendering another potent advantage: his brand as an economic populist loathed by the financial elite and planning to raise taxes on rich people like himself.

Probably nothing has done more to erode Trump’s public standing than the consistently plutocratic cast of his domestic policy. The tax cut is the second-most-unpopular major piece of legislation in recorded history, behind only Trump’s other major domestic initiative, the health-care-repeal bill:

Chart:: The Washington Post

Democrats have nothing to fear from making repeal of the Trump tax cuts for the rich a defining party plank. On the contrary, they have a great deal to gain. The bill is a cash grab by the wealthy, driven by the demands of the Republican donor base, and stuffed with targeted favors for insiders with lobbyists. Many more are sure to surface. The more they talk about it, the more Democrats can drive home the message that Trump’s economic populism was a fraud.

In the 2020 campaign, Democrats are inevitably going to propose new social spending. Reporters are inevitably going to ask them how they plan to pay for it. Republicans have given them an easy answer: Repeal the Trump tax cuts for the rich.

The architects of the Trump tax cuts have dreamed of reshaping the tax code in a permanent way. Permanence means more than the technical absence of an expiration date. It has stood for the party’s ambition to leverage the Trump administration and their control of government into something deeper. “Once in a generation or so, there is an opportunity to do something transformational — something that will have a truly lasting impact long after we are gone,” Paul Ryan declared earlier this year. “That moment is here and we are going to meet it. Ladies and gentlemen, we are going to fix this nation’s tax code once and for all.”

Their “fix” is a cash grab. It is “permanent” only until Democrats regain control of government. And thanks to the Trump tax cuts, that day will come sooner.