What did Donald Trump do today?

He lied about his budget bill.

Trump signed his budget bill into law today as part of a White House Independence Day ceremony. According to nonpartisan experts including the Congressional Budget Office, the bill is expected to add $3 or $4 trillion to the national debt, cause 17 million Americans to lose their health coverage, and make permanent Trump's 2017 tax cuts that exclusively benefit the very wealthiest Americans while cutting services for everyone else. It will also massively expand the size of ICE, ballooning its budget overnight into something bigger than the entire military spending of some of the world's largest nations.

None of these things are popular. In fact, Trump's budget bill is the second most unpopular piece of legislation in the last 35 years, topped only by his failed attempt to repeal the Affordable Care Act in 2017.

Republicans in both chambers—including some who voted for the bill—warned their colleagues that the clear public opposition to the bill was political suicide for the midterm elections. That may explain why Trump said this today:

It's the most popular bill ever signed in the history of our country. Whether you're military or anybody else, this is the most—single most popular bill ever signed.

As is often the case with these kinds of bizarre denials of reality from Trump, it's not clear whether he's deliberately lying or has no idea what he's talking about. He appeared genuinely confused earlier this week about whether the bill had anything to do with Medicaid. (It cuts Medicaid by one trillion dollars, almost precisely the amount needed to offset the tax breaks for the ultra-wealthy.)

Trump also repeated a lie about Social Security, claiming that his bill ended taxation of its benefits. In fact, it has no effect at all. Most seniors don't pay income tax as it is, but those who do will still see that income taxed. The Trump Administration sent an e-mail overnight repeating this lie directly from the Trump-appointed head of the Social Security Administration, praising Trump by name for fulfilling his "promise."

Trump did campaign on that still-unfulfilled promise to end taxation of Social Security benefits, something that would have been far more popular than most of the actual provisions in the bill and faced little opposition in Congress—if he had bothered to put it in.

Why does this matter?

• Reality doesn't change just because Donald Trump tells it to. 

• Presidents who pass genuinely popular legislation don't have to demand that people pretend it was popular. 

• If Trump wasn't lying, then he's incapable of understanding that he's being systematically lied to, and is unfit for office on those grounds.