“Deals are my art form,” Donald Trump has said. “I like making deals, preferably big deals.”

What bitter irony, then, that Trump himself is the reason dealmaking in Washington has completely collapsed.

Over the past few days, I’ve been asking congressional Democrats what kind of deal they might accept from Trump to give him his wall and end the shutdown. Would a solution for DREAMers do it? A solution for DREAMers plus resources for the humanitarian crisis that’s actually playing out on the border? Something totally different? Do they see the wall as tradable in a deal at all?

Turns out I was asking the wrong question.

I’ve covered more than my share of shutdowns (to say nothing of debt ceiling crises, sequestration deadlines, and assorted other high-stakes congressional ridiculousness) and I know their rhythms. By now, we should be well into the let’s-make-a-deal stage. By now, congressional staffers should be coming up with all manner of possible bargains, some realistic and some less so. But we’re not.

Before you can imagine a deal you have to believe there’s someone to make a deal with. And that’s where this process is stuck. Congressional Democrats don’t believe they’ve got a partner for a deal. Any deal they make with congressional Republicans — like the spending deal that was supposed to avert this whole shutdown mess in the first place — can be abrogated by a presidential tweet. And any deal they make with President Trump can be abrogated by, well, President Trump.

“Unless the president not only publicly announces support but publishes bill text and whips it, there’s no way it wouldn’t get blown up by Miller and Bannon,” says Sen. Brian Schatz (D-HI).

The disillusionment is well earned. Over and over again, Democrats have shaken hands on an immigration deal with Trump, only to see him abandon it as soon as they leave the room. Nor is this ancient history. Trump went back on his word during the negotiations that led to the current shutdown. That was less than a month ago.

The White House “can’t stick to any offer for longer than 10 minutes on this,” says an aide to House Democratic leadership, with evident disgust.

This is the bitter irony of Trump’s presidency: The candidate who ran as the greatest dealmaker the country had ever seen has proven to be the worst. Deals are built on trust. If you give something painful to receive something important, you need to trust that you’re actually going to get what you were promised.

Trump has repeatedly betrayed that trust — and not just with Democrats. The result isn’t just a difficulty reaching deals with Trump, but a skittishness in proposing them, or even entertaining them. Deals, after all, are dangerous.

When congressional Democrats offer real concessions to the president, they face blowback from their own constituents, and members of their own caucus. That backlash may be worth bearing to get the deal done, but it’s pure pain if the president then decides to abandon the bargain because he doesn’t like how he’s being talked about on Fox & Friends, or because the next adviser who walks into the Oval Office changes his mind.

Trump, meanwhile, has no interest in making a deal himself. He storms out of meetings, insults his interlocutors, and offers no concessions. I’ve long thought that Trump doesn’t actually want a deal on the wall — he wants to be seen fighting for it, not to actually compromise to get it — and nothing in his behavior has yet proven me wrong.

Tellingly, Trump now seems to be gravitating toward trying to declare a state of emergency, which wouldn’t get him the money for his wall and would probably tie the project up in court till long after Trump’s presidency, but at least Trump could declare victory without giving anything up. At least, in other words, he could avoid the hard work of actually making and selling a deal.

There are many ways Trump is bad at being president, but this is one of the most consequential, and most surprising. The business of divided governance runs on dealmaking, and Trump himself has become the obstacle to serious, successful negotiations. Of all the overhyped, underpowered products and promises to bear Trump’s name, none has been as much of a scam as his reputation as a dealmaker.