This chart, from Bloomberg News, illustrates a key problem for President Trump. The blue line is the unemployment rate. The white line is the percentage of consumers who expect unemployment to fall.

The last time that as many people thought the unemployment rate was going to decline was in the early 1980s, when the rate was near 9 percent. In general, the percentage of people who think the unemployment rate will decline tracks with the rate itself. When it’s lower, fewer people think it will drop — because it can’t keep going down forever.

Since the presidential election, though, the two lines have been trending in opposite directions. The unemployment rate is near a low for the past decade, but there has been a sudden spike in optimism that it will keep falling further. In part, this is because supporters of President Trump have suddenly gained more confidence in the economy, something we’ve seen in polling. Before the election, 80 percent of Republicans said the economy was getting worse. A week later, nearly half said it was getting better.

Part of the unemployment question, too, is based on Trump having repeatedly singled out the unemployment rate on the campaign trail. He continually insisted that the “real” rate was much higher, sometimes suggesting it was over 40 percent. If you support Trump and you think the unemployment rate is that high, you are probably confident that he’ll reduce it.

But for everyone else, people who understand that the rate isn’t that high, the question becomes how Trump can fulfill his promises. One possibility is that he will goose the numbers. There’s a more likely answer, though: He’ll just change his story.

Consider this legitimately jaw-dropping sentence from Trump’s interview with “Fox & Friends” on Tuesday.

“My generals are the most respected that we’ve had in many decades.”

The context for the comment is important, too: He was talking about a raid in Yemen that killed a Navy SEAL. After explaining that it was “a mission that was started before I got here,” Trump said it was something that “they” — the generals — “wanted to do.” There’s an abdication of the “buck stops here” mentality of Harry S. Truman in those comments, certainly, but, again, let’s focus on the generals.

Trump’s generals — the high-ranking leaders of the armed forces — have nothing to do with Trump. His defense secretary certainly does, of course, as would other executive branch appointees (of whom only one has been announced without withdrawing). But the generals have worked themselves up through the ranks to their positions over years. They are the same generals who were in place before Jan. 20, under President Barack Obama. The Joint Chiefs are the same. The generals may be the most respected the nation has had in decades, but they’re not Trump’s generals.

What makes that comment particularly egregious is that they’re the same generals Trump was slagging on the campaign trail.

In a town hall meeting in September on the aircraft carrier Intrepid in New York, Trump disparaged U.S. military leaders in unsparing terms. Moderator Matt Lauer asked Trump if he stood by past comments that he knew more about fighting the Islamic State than the generals.

“Well, the generals under Barack Obama and Hillary Clinton have not been successful,” Trump said. “I think under the leadership of Barack Obama and Hillary Clinton, the generals have been reduced to rubble. They have been reduced to a point where it’s embarrassing for our country.”

When Trump said he would convene generals to put together a plan for that fight, Lauer asked why, given that he apparently had little confidence in their abilities.

“Well, they’ll probably be different generals, to be honest with you,” Trump replied.

Again: These are the same generals. These “rubble” generals who have “not been successful” are the ones that Trump now claims as his own and “the most respected that we’ve had in many decades.” He disrespected them himself on the campaign trail! But, you know. That was then.

That’s the key to how this whole thing will work for Trump. The numbers may not change, but the messaging will. He already has made it obvious that many people will accept what he says as true, regardless of a statement’s connection to reality. So he’ll just take credit for the generals he disparaged or, perhaps, take credit for the unemployment rate he just dismissed as fake.

There was a tiny moment of self-reflection in that interview with “Fox & Friends.” Asked to grade himself, Trump for once didn’t stamp his report card with all big league A-pluses.

“I think I get an A in terms of what I’ve actually done,” Trump said, “but in terms of messaging, I’d give myself a C or a C-plus.”

That’s probably backward. He has done less than he likes to acknowledge — but has done a very good job of convincing people that he has seized the bull by the horns. He has great generals! Now we’ll see what he can do about that 40 percent unemployment rate.