There was a staggering amount of nonsense emanating from the White House on Friday in response to the latest quarterly GDP data. The numbers looked great – 4.1% growth between April and June – but they were skewed by some one-time factors; economists expect much slower growth in the second half of the year; and quarterly growth and annual growth aren’t even close to being the same thing.

Donald Trump, his team, and their allies nevertheless launched a massive public-relations campaign rooted in shameless deceptions. It was as cynical a move as any this White House has made, counting on the public to be too ignorant to see through the bogus sales pitch.

But as it turns out, the president wanted to go a little further. New York magazine highlighted the second part of Trump’s p.r. strategy: setting expectations for the future.

[W]hen the Commerce Department revealed Friday that the U.S. economy had grown 4.1 percent last quarter, the president did not respond by cautiously tempering expectations for future growth. Instead, Trump assured Sean Hannity that the economy is “going to get better”; that he will cut the trade deficit in half; deliver 8-to-9 percent GDP growth; and turn the projected $1 trillion budget deficit into a surplus. “The economy, we can go a lot higher,” the president told Hannity in a surprise radio interview Friday afternoon. “We have $21 trillion in debt. When this really kicks in we’ll start paying off that debt like water.”

Not to put too fine a point on this, but the president’s comments were basically gibberish, reflecting someone who lacks even a basic familiarity with the underlying issues. For example, Trump is needlessly obsessed with the trade deficit – no one at the White House has explained why – and if he genuinely believes he can cut it in half, in the process creating 9% GDP growth, he has no idea what he’s talking about.

As for the idea that he can start paying off the national debt “like water,” that would first require Trump to eliminate the deficit – which is currently not even shrinking but rising quickly to historical heights, thanks almost entirely to Republican tax breaks for the wealthy that the president didn’t even try to pay for.

But even putting the factual details aside, there are important political reasons for Trump to steer clear of this rhetoric.

Let’s say Donald Trump doesn’t care about telling the truth. I know, it’s hard to imagine, but consider the thought experiment. Under these circumstances, he’d be inclined to peddle all kinds of nonsense about massive economic growth, eliminating the deficit, paying off the national debt, etc.

But the trouble comes, not when fact-checkers point the scope of the president’s dishonesty, but when the predicted results fail to materialize. In politics, it’s always better to under-promise and over-deliver. Trump is over-promising and setting standards on which he’ll never be able to deliver.

This started with Candidate Trump. As we discussed a few months ago, Trump routinely promised “4% annual economic growth” – and in some cases, he suggested his policies could push growth to as high as 6%.

We already know he’s not going to generate these kinds of results. Faced with that reality, the smart move for Trump would be to start lowering expectations. Instead, the president is talking about even more ridiculous economic projections, which will only make decent progress look like failure when the actual data falls far short of his absurd chest-thumping boasts.

Trump’s predictions aren’t just dishonest; they’re counter-productive. The lying is annoying, but the specific nature of these deceptions will only make things worse for the president.