WASHINGTON -- One of President Trump's favorite words is "strong." His obsession with strength leads him to a love for unilateral announcements, denunciations of staff members by way of showing who is in charge, and Twitter wars designed to prove that he will not back down from any fight.

Yet Trump is also a pleaser who likes to make those in his immediate company happy by persuading them that he is absolutely on their wavelength. You could see this in his flip-flopping on policy toward both guns and immigration. Recall that the positions he took on any given day depended upon who was in the room with him.

Eventually, he will default to preserving his electoral standing. He was never likely to break with either the National Rifle Association or the hardline nativists who are at the heart of his administration and his political base. Trump has interests. He doesn't have a philosophy.

But above all, he has needs, and the erratic nature of the Trump presidency can be explained by the interaction of his two compulsions -- looking strong and being liked. They sometimes seem to collide, but they are actually of a piece. Both speak of a man for whom the personal is the only kind of political. It is impossible to know what his true policy commitments are because they are secondary. On any given day and at any given moment, his actions are dictated by what, in his eyes, will make him look forceful and bring him accolades.

Bear all this in mind in assessing the two major events of recent days: Trump's tariffs on steel and aluminum, and his agreement to enter direct talks with North Korean dictator Kim Jong Un.

The tariffs may, in fact, serve him well in the short-term. Note that Trump initially reached his decision to impose them when he was feeling "angry" and "increasingly isolated," as Washington Post reporters Philip Rucker, Ashley Parker and Josh Dawsey wrote on March 3. With the investigation by special counsel Robert Mueller gathering steam and other scandals dominating the airwaves, Trump did what he always does: He sought to change the subject and shake up the news cycle.

But there is more. If Trump and the Republicans have reason to worry that the political energy of his foes could play out in substantially increased Democratic turnout in this November's elections, there is a second danger almost as serious. His working-class supporters -- the key swing group in the states that gave him his Electoral College victory -- have little to show for his presidency.

While last Friday's robust jobs report provided continued good news overall, it found that wages were nearly flat. And as Post blogger Greg Sargent observed last week, economic growth remains concentrated in the states that rejected Trump. "Trump Country" is not experiencing the renaissance he predicted, in part because he could not have kept his outsized promises in the first place.

Thus Republican nervousness about Tuesday's special election for a Congressional seat in western Pennsylvania. If Republicans lose or win very narrowly, it will show they face decimation in suburban areas long hostile to Trump, but also in his heartland.

Trump scaled back the tariffs from his original proposal, but they still sent a loud message to his straying base: Remember the old me; I'm still here. He conveyed an aura of strength even as he curried favor with voters he badly wants to hold on to. Should the GOP prevail on Tuesday, count on Trump to tout the tariffs opposed by most of his party as what pulled it over the line.

His agreement to meet with North Korea's brutal and erratic leader is an even bigger show-stopper. It was variously cast as a great triumph for Trump's hard line, or a foolish and premature concession that enhanced Kim's standing without gaining anything in return. On Friday the White House conditioned the entire initiative on "concrete steps" from North Korea without specifying them. But there was a Trumpian point to it all. He was doing something no other president dared do while casting himself in a starring role.

All presidencies are shaped by the personal proclivities of the occupant of the Oval Office. But we have not had a president who focused so much energy on appearing to be strong and who, like the playwright Arthur Miller's salesman Willy Loman, so desperately wants to believe he is "liked." These drives are the biggest threats to Trump himself, and, I fear, to our republic.

(c) 2018, Washington Post Writers Group