Stop me if you’ve heard this before. A G.O.P. presidential candidate loses the popular vote, but somehow ends up in the White House anyway. Despite his dubious legitimacy, his allies in Congress take advantage of his election to ram through a huge tax cut that blows up the budget deficit while disproportionately benefiting the wealthy. While the big bucks go to the big incomes, however, the tax bill does throw some crumbs at the middle class, and Republicans try to sell the bill as a boon to working families.

So far this account applies equally to George W. Bush and Donald Trump. But then the story takes a turn. The Bush sales job was effective: While the 2001 tax cut wasn’t overwhelmingly popular, more people approved than disapproved, and it provided the G.O.P. with at least a modest political boost. But the Trump tax cut was unpopular from the start — in fact, less popular than past tax hikes.

And this tax cut doesn’t seem to be winning more support over time. Most Americans say they don’t see any positive effect on their paychecks. Public approval of the tax cut seems, if anything, to be falling rather than rising. And Republicans have pretty much stopped even mentioning the bill on the campaign trail.

Which raises the question: Why doesn’t snake oil sell like it used to?

In the past, deficit hypocrisy was an important weapon in the G.O.P. political arsenal. Both parties talked about fiscal responsibility, but only Democrats practiced it, actually paying for policy initiatives like Obamacare. Yet Democrats were punished for doing the right thing — remember “they’re taking $500 billion from Medicare”? — while Republicans seemingly paid no price for their cynicism. Voters focused on the extra money in their pockets, ignoring the long-run consequences of big tax cuts for the rich.