Donald Trump has done a lot of dumb things as president, like thinking he could saunter into a summit with a nuclear-armed enemy and change world history without so much as reading one paragraph to prepare. And he’s done a lot of ghastly things, like obstruct justice, break the law by paying off past conquests, defile the office, etc.

But all those things are uniquely Trumpian. This week marks the first time he’s done something just conventionally politically stupid. OK, probably not the first time, but the most notable time. This budget his administration put out is a howler. And I think that by the time we get into the heat of the 2020 election, it’s going to prove to be the biggest own-goal Trump has committed in the course of his entire term.

It’s unbelievable. It makes Simon Legree look like Santa Claus. Every caricature you’d want to make of a Republican budget, it opens itself up to. It’s horrible to the environment. It’s heartless to poor people. It wants to give people on food stamps box lunches again (remember that debacle, from the first budget?).

But more than that—it goes back on his big yuuuge promises from 2016. I’ll never cut Social Security or Medicare, he said then. Never! “I’m not going to cut Social Security like every other Republican,” he said while campaigning. “I’m not going to cut Medicare or Medicaid.”

And what’s he doing now? Cutting Social Security and Medicare and Medicaid. He’ll say he’s not, and the Republicans will say he’s not, but he’s cutting them all. Not in nakedly obvious ways. They’re smarter than that of course. The Social Security cuts are to SSDI, mainly, the disability program, which doesn’t affect that many people in the grand scheme of things. But they’re real cuts to real people. So, he lied.

OK, “Trump lied” is by now the snooziest headline in the business, but here’s what makes this particular lie worth thinking about for a minute.

You know how people like me write all the time and say on TV all the time that Trump has taken over the Republican Party? Well, we write and say it because it’s true most of the time. But the budget, which is to say the economic policy of Donald Trump’s administration, is one matter on which Trump has not taken over the Republican Party. The Republican Party has taken over him.

If Trump had taken over the Republican Party on economic policy, we would have seen by now something weird and interesting, like the closing of the carried-interest loophole for hedge fund managers, which Trump used to say half-heartedly he supported doing (and which got gullible commentators to note how “interesting” he was).

But of course we’ve seen nothing of the sort. We’ve seen them pass exactly one bill, which was a massive tax cut to corporations, reducing their rate by more than they were even seeking, and to the top 1 percent.

It was all too easy to see at the time where this was headed. I wrote the day after the bill passed:

You think this is bad, think about what’s next. What’s next are cuts to Medicaid, Medicare, Social Security, and other domestic spending programs. Because this is the Republican formula: 1. Pass massive tax cuts for the top 1 percent. 2. Run up the deficit. 3. A year or two later go, “Oh my God, look at the deficit! This proves that spending is just out of control!” 4. Start taking the axe to entitlement programs and the domestic discretionary budget.

Yes, I was right about every single detail, but look, I’m no genius. This was easier to predict than USC being involved in that college scam (and I kinda like the Trojans, but, come on). They’ve been reading from the same script for 30 years.

The budget deficit right now is back over $1 trillion. Largely because of the tax cuts. And on cue, they scream about runaway spending. And it has to be taken out of the hides of poor children. But not defense contractors!

This is the biggest, fattest hanging curveball over home plate for the Democrats since Steve Blass lost his fastball and Johnny Bench stepped into the batter’s box (and if you get that reference, I automatically love you, even if you’re a Republican).

Sometimes, liberalism can be hard to explain to people, a lot harder than conservatism, because it requires a connecting of dots that conservatism doesn’t require. “I’m gonna cut your taxes” is a lot easier to say to people than “I’m going to increase your taxes a little, but for this very specific need, and while it’s true you won’t see the fruits of it for two or three years, I’m still asking you to take it on faith…”

But the dots here are as big as clouds in the sky. Joe Biden connected them the other day when he spoke to those firefighters: “Did you see the budget that was just introduced? It cuts $845 billion... in Medicare and... $240 billion in Medicaid. Why? Because of a tax cut for the super-wealthy that created a deficit of $1.9 trillion and now they’ve got to make somebody pay for it.” Boom. Just say it and say it and say it.

I’m a little surprised Trump has opened himself up to this line of attack, and to the standard “heartless Republicans” broadsides. They work. Not showily, but they work. Most people don’t like heartless budget and entitlement cuts. It surely hurt Hillary Clinton’s campaign that she couldn’t launch the standard lines of attack that Democrats have always used against Republicans because Trump said he was different.

Well, now he’s the same. Trump has proven stronger than most Republicans in most respects, as they’ve abased themselves to him on nearly every front. But there is one thing Trump is not stronger than. The GOP has given him their traditional mean gene.