'Presidential" is an overused adjective that comes from "president." Anything a President does is presidential. Therefore everything Donald Trump does is presidential. His words are presidential. His extra-long neckties are presidential neckties, because he wears them. They are the neckties of the President.

But Mr. Trump, whose approval ratings are among the lowest ever for a new president, needs to be a different kind of "presidential" – the kind that describes the reassuring temperament and competence of a respected American leader.

So on Tuesday night, he addressed the U.S. Congress with a speech designed with that in mind. He read from a teleprompter and didn't interrupt the script with his usual repertoire of ad-libbed marketing superlatives and tautological overreach. He spoke of harmony and peace, and of achieving impossible dreams. He evoked American resolve. He called for unity. He was sentimental and jingoistic.

Story continues below advertisement

For subscribers: Trump's blueprint for America meets sobering Washington realities

Opinion: The President finally looked presidential. But will it last?

For subscribers: Foreigners nasty, but you're okay: Five Trump takeaways for Canada

"A new chapter of American greatness is now beginning," he said.

The speech was a success, to a point. Some previously critical pundits spoke of a "pivot"; of the "moment when Trump became President." It was reassuring for them and others to see Mr. Trump act out the role of President as it is embroidered in the American imagination – the wise and protective leader carrying the great nation forward.

But there was a Trumpian darkness underneath it. The President painted a false picture of a country besieged by drugs, criminals and terrorists. He announced a new Homeland Security department that will focus on crimes committed by illegal immigrants, for no other purpose than to demonize them. He mentioned American global leadership, and a few sentences later rejected the idea of American global leadership.

Delivered by any other president, it would have a garden-variety political speech by an unpopular leader: big on rhetoric, devoid of specifics and economical with the truth.

Story continues below advertisement

But because it was by the unconventional Mr. Trump, the speech took on additional meaning. He used a teleprompter! He didn't ad lib! He seemed ... presidential!

Mr. Trump did his best impersonation of a President. For some people, it was impressive. But it would be unwise to think this is the beginning of a new era. He's still Donald Trump.