As he took the oath of office and became America’s 45th president Friday, Donald John Trump vowed to put “America first” as he embarked on a “great national effort to rebuild this country and restore its promise for the American people.”

That was today.

The Republican’s biggest challenge, as ever, is whether his message will survive another 24 or 36 hours, or however long it takes before a slight to his ego provokes yet another 3 a.m. Twitter storm that undoes his admittedly workmanlike rhetoric.

The 18 unusual months that have elapsed since Trump went from national punchline to resident of 1600 Pennsylvania Avenue suggests that’s probably inevitable, as Americans wake up Saturday to the first, full day of the most unusual presidency in recent memory.

But on Friday, at least, Trump struck his most conciliatory tone to date, evoking an America stretching from the “urban sprawl” of Detroit to the prairies of Nebraska where Americans whether black, white or brown “bleed the same red blood of patriots.”

He promised to “build new roads and highways and bridges and airports and tunnels and railways all across our wonderful nation. We will get our people off of welfare and back to work, rebuilding our country with American hands and American labor.”

And he promised to “bring back our jobs. We will bring back our borders. We will bring back our wealth. And we will bring back our dreams.”

So far so good. But wait for it.

Clocking in at a little more than 16 minutes, Trump’s speech was a restatement of familiar campaign themes: shuttered factories, porous borders and a Washington that no longer cares.

“This is your day. This is your celebration,” Trump said, not really giving Americans much to celebrate. “And, this, the United States of America, is your country.”

He went on to recite a litany of woe, a country where “mothers and children [are] trapped in poverty in our inner cities; rusted out factories [are] scattered like tombstones across the landscape of our nation; an education system flush with cash, but which leaves our young and beautiful students deprived of all knowledge; and the crime and the gangs and the drugs that have stolen too many lives and robbed our country of so much unrealized potential.”

He ended with a depressing flourish: “This American carnage stops right here and stops right now.”

Trump’s solution: A policy that puts “America First,” a governing philosophy based on the premise that “every decision on trade, on taxes, on immigration, on foreign affairs will be made to benefit American workers and American families. We must protect our borders from the ravages of other countries making our products, stealing our companies and destroying our jobs.”

For those old enough to remember, “America First” has some far more sinister roots in American history. It was claimed first in the 1930s by a starkly isolationist group that preferred a negotiated peace with Adolf Hitler, even if it meant England was on the verge of defeat.

Indeed, Trump suggested an altered American relationship with the nation’s historic allies in western Europe, retreating from the interventionist ideals that have helped keep the peace for 70 years.

“We will seek friendship and goodwill with the nations of the world, but we do so with the understanding that it is the right of all nations to put their own interests first,” he said “We do not seek to impose our way of life on anyone, but rather to let it shine as an example. We will shine for everyone to follow.”

In other words, welcome back to Fortress America.

No politician has ever lost money running against Washington, and Trump wasted little time teeing off on a governing establishment that “protected itself but not the citizens of our country.”

“Their victories have not been your victories,” he said. “Their triumphs have not been your triumphs. And while they celebrated in our nation’s capital, there was little to celebrate for struggling families all across our land.”

There Trump either forgot — or deliberately overlooked — the fact that he’s stocked his first cabinet with the same millionaires and billionaires who plunged the country into the Great Recession.

So, here’s hoping that the America evoked in the first half of Trump’s speech is one that survives the day — one united in common purpose — not the one peering in fear over a walled-up border at a world filled with threats.

Experience suggests the latter.

An award-winning political journalist, Micek is the Opinion Editor and Political Columnist for PennLive/The Patriot-News in Harrisburg, Pa. Readers may follow him on Twitter @ByJohnLMicek and email him at jmicek@pennlive.com.