Donald Trump did himself a world of good Tuesday night. After a nasty 17-month campaign for the White House, a rocky two-and-a-half-month transition, and an often alarming first month in office, Trump finally managed to sound like a president. If this disciplined, focused Trump sticks around, his approval rating will soon rebound, getting him within striking distance of 50 percent — and Democrats will find themselves in a terrible bind.

This isn't about a "pivot." On substance, Trump was very much himself. He hit all of his usual themes. In addition to the standard Republican promises — to repeal and replace ObamaCare, to increase defense spending and defeat "radical Islamic terrorism" — he vowed to crack down on illegal immigration, stop unfair trade practices, fight crime, and pursue massive infrastructure projects, with all of it backed up by generous dollops of demagoguery. There was plenty for liberals, libertarians, and "conservative movement" Republicans to object to.

In that sense, nothing had changed. Trump was Trump — the scourge of the country's political establishment, an unapologetic nationalist, and a populist with protectionist instincts.

Except this time, it sort of worked.

Instead of acting like an angry, petulant blowhard, he sounded restrained, measured, almost like a statesman (including his opening, unambiguous denunciation of recent anti-Semitic attacks). There were no verbal assaults on the media, no insults hurled at an endless list of enemies. He spoke darkly about the country's many problems, but he didn't paint a vision of "American carnage," as he did in his much shorter and much more combative and militant inaugural address. This time the darkness was laced with repeated, stirring calls for unity, a coming together to bridge our many deep differences.

Was the message faintly ridiculous coming from Trump, the most starkly polarizing figure in recent American history? You bet it was. But that didn't make the gesture toward national reconciliation any less likely to find a receptive and grateful audience.

The difference was one of tone. Up until now, Trump has sharply diverged from Ronald Reagan not only on issues (immigration, trade, foreign policy) but also in disposition. Reagan was an inveterate optimist whose love for America and hope for its future was infectious. Just about every speech he gave as president, regardless of its subject matter, ended up serving as a national pep talk.

By contrast, Trump's speeches have until now come off as hectoring, bleak, bullying, like the barked orders of an angry drill sergeant. But not on Tuesday night. Trump talked slowly, demonstrated restraint, stuck closely to the prepared remarks, and remained in control of his delivery — all of which allowed the audience to focus on the message, which for the first time in a Trump speech effectively — and, for the most part, convincingly — mixed harsh descriptions of the nation's problems with hope for a better American future.

For the very first time, Trump managed to be presidential.

That could be a big problem for Democrats. Ever since inauguration day, Trump's behavior has been so erratic and the actions of his administration so unprofessional, incompetent, and even quasi-authoritarian that his opponents have been able to portray his unorthodox policy agenda (combining multiple items on the right-wing Republican wish list with purely nationalist proposals) as seamlessly connected — and perhaps even the advent of autocracy in America.

But a strange thing happened on Tuesday night. Democrats and other media critics responded to the speech on Twitter with the usual stream of snark and foreboding — except this time, for the first time, there was a palpable disconnect between the claims of the critics and the subject of their criticism. Trump was no longer the would-be tyrant shredding America's hard-won, cherished democratic norms. He was a president pushing an admittedly unusual and in many ways extreme policy agenda, but doing so while playing by the rules.

The mantra of the past four months — "This is not normal" — finally got reversed. Trump delivered a remarkably normal speech. That in itself is not normal. Democrats better hope it stays that way.