Washington — For the new year, critics of President Trump should resolve not to be intimidated by the potential wrath of his vaunted political base. The only one who should cower before the Make America Great Again legions is Trump himself.

And he does fear them, bigly. The latest illustration is the way he chickened out on a bipartisan agreement to keep the government fully funded, instead forcing a partial shutdown over chump change for “the wall.” I use quotation marks because there never was going to be an actual, physical, continuous wall along the U.S.-Mexico border, much less paid for by the Mexican government. The president is desperately trying to avoid acknowledging this and other realities before the 2020 election.

Anyone who thinks Trump is a master politician is wrong. He’s a master illusionist, which isn’t the same thing. Politicians can’t keep pulling rabbits out of empty hats forever. At some point they face a reckoning, and Trump’s is well underway.

Trump is talented at making it appear he has more than he really does — more money, more respect, more support. All those campaign rallies before the midterm election were not just an attempt to save the Republican majorities in Congress or feed Trump’s insatiable ego. They were also demonstrations of the fervor of his core supporters — and implied warnings to Republicans who might cross him.

Trump tries to project an image of immense strength. But it turns out that the man who made “You’re fired!” a television catchphrase can’t summon the nerve to actually dismiss anyone in person. Trump’s bluster camouflages great weakness.

Look at his political standing. Trump won the presidency with 46 percent of the popular vote. (That’s compared to 48 percent for Hillary Clinton, but who’s counting?) His margin in the Electoral College, which he tries to portray as a great landslide, was actually quite puny — smaller than either of Barack Obama’s, either of Bill Clinton’s, the late George H.W. Bush’s or either of Ronald Reagan’s.

Trump did have a bigger electoral margin than George W. Bush ever managed to win. But only Trump has the unflattering distinction of winning a presidential election while losing the popular vote by nearly 3 million.

No matter. A skilled politician would seek to expand his base of support. But according to Gallup, Trump’s approval has been underwater since the day he took office — never once reaching higher than 45 percent — and now stands at 39 percent.

Does that apples-to-oranges comparison of vote percentage and approval rating really mean that Trump has lost significant support? Not necessarily — until you also take into account the results of the midterm election, which can only be read as a massive repudiation of Trump and all he stands for. Democrats captured the House, defended all but two of their imperiled senators, and grabbed governorships and state legislatures across the country. The Democratic Party’s House popular-vote margin was the biggest ever seen in a midterm.

So much for the ethno-nationalist-populist wave that Trump is supposed to be surfing.

It is a mistake to underestimate Trump’s base or to suggest that all the issues he raises are, because he raises them, invalid. There are legitimate reasons, for example, to want to ensure border security. But racism is not one of them; and a useless wall, meant to symbolize rejection of a brown-skinned “invasion,” is not an actual solution.

The fact is that Trump touched a nerve that was already inflamed. Race, ethnicity, cultural heritage, economic dislocation, opioid addiction, the effects of free trade, the impact of robotics — all these issues were out there already, and a lot of people believed our elected officials weren’t dealing with them adequately. Trump hasn’t a clue about what to do or how to do it. But he knows how to poke and prod; he knows how to rile people up and sell them red hats.

If his core, unshakable base of support is, say, around 35 percent, then he almost surely would lose a re-election bid in 2020. I say “almost” because we don’t know whom the Democrats will run against him or whether there will be a significant independent or third-party challenger; and I say “would” because we can’t be entirely sure that Trump will run again.

For now, he may be calculating that 35 percent is enough to keep the GOP-led Senate from removing him from office in the event that the House finds compelling grounds to impeach him. What keeps him from compromising isn’t principle or determination. It’s simple fear.

— Eugene Robinson is a columnist for Washington Post Writers Group.