Donald Trump’s Inaugural Address on Friday was a scalding repudiation of the Washington establishment. The question left hanging after this angry jeremiad: How will the new commander-in-chief be able to work with these people to govern the country?

Uncompromising in tone and entirely in keeping with his insurgent campaign, Trump dispensed with appeals to unity or attempts to build bridges to his opponents. He tarred the nation’s political class, arrayed behind him on the West Front of the Capitol, as faithless and corrupt.

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

“That all changes,” a grimfaced Trump declared, “starting right here, and right now.”

From Ronald Reagan to Barack Obama, presidents have come to Washington as agents of change and enemies of the status quo. Most have discovered, to their benefit or misery, that they must work the levers of government to push through their agenda. But none in recent memory has appeared so ready to lead by going to war against the existing order.

In fact, Trump is as close to an independent as has ever served in modern times. He ran against his own party’s establishment as much as he ran against Hillary Clinton. In his address, he made no reference to the Republican leadership in Congress, and said nothing about working with Speaker Paul Ryan or Senator Mitch McConnell to advance a legislative agenda. His views on trade, foreign policy and the role of government are at odds with Republican orthodoxy, setting the stage for a clash between the party and its standard-bearer.

There were signs, under the leaden skies on the National Mall, that Trump’s opponents will return the favour. The Senate minority leader, Chuck Schumer of New York, issued a blunt warning to Mr. Trump, moments before he was sworn in, that the American people would stand up for the rule of law, a free press — the things, he said, “that make America America.”

Schumer quoted from a farewell letter that a Union soldier, Maj. Sullivan Ballou, sent to his wife during the Civil War, days before he was killed in the First Battle of Bull Run. The doomed soldier’s words — in which he recalled the sacrifices made by those who founded the nation — could provide solace in the days to come, Schumer said.

Democratic lawmakers wore buttons on their lapels that said “Protect Our Care,” a reference to the landmark health care law that Trump and Republicans in Congress have promised to overturn. About 60 Democrats boycotted the ceremony altogether — a movement that picked up steam after Trump clashed with Representative John Lewis of Georgia, after Lewis said that he did not view him as a legitimate president.

“There was very little in this speech that would offer comfort to a Trump opponent or skeptic,” said Michael Beschloss, the presidential scholar. “It had the texture more of a convention or campaign speech than what we usually hear in an Inaugural Address.”

And yet, Trump has presented himself as a dealmaker, not an ideologue, and it remains on open question whether he will remain the relentless populist who was on display on Friday.

For all the public tension between Trump and Schumer, the president has reached out to his fellow New Yorker, whom he has known for decades. He has named cabinet members who have split with him on issues like banning Muslims or torturing suspected terrorists. He has suggested that his own views themselves are a work in progress.

In the 76 days since his election, Trump has shown a quicksilver ability to shift his positions on major issues, like his campaign promises to repeal of the Affordable Care Act and build a wall on the Mexican border and make Mexico pay for it. He mentioned neither in his speech.

Trump, his aides like to say, is a direct descendant of Andrew Jackson, the nation’s first populist president. Populists in the Jackson tradition, political theorists say, are protean in character.

“They’re kind of like the moon,” said Walter Russell Mead, a professor at Bard College and a scholar at the Hudson Institute who has written extensively about Jackson’s influence.

“They’re the brightest object in the night sky when the moon is full, but they wax and wane.”

On Friday, Trump’s moon was full. He dispensed with the usual grace notes of inaugural speeches, not even mentioning or shaking the hand of his vanquished opponent, Hillary Clinton, who sat watching with her husband, Bill Clinton. (Trump did recognize the Clintons at a lunch at the Capitol after the ceremony.) While he thanked former president Barack Obama and his wife, Michelle, for their “gracious aid” during the transition, he described the country Obama left behind as a kind of Mad Max-like dystopia.

Using dark language reminiscent of his acceptance speech at the Republican National Convention, Trump talked about “mothers and children trapped in poverty in our inner cities; rustedout factories scattered like tombstones across the landscape of our nation,” schools that teach students nothing, and “crime and gangs and drugs that have stolen too many lives and robbed our country of so much unrealized potential.”

Lest Republicans become complacent, Trump made it clear that he believes he is leading a populist movement that has little regard for any party platforms or loyalties. He thundered against free trade, a pillar of the Republican Party, as he had during the campaign.

He promised a Franklin D. Roosevelt-style public works campaign — “new roads and highways, and bridges, and airports, and tunnels, and railways all across our wonderful nation” — something the Republicans would have implacably opposed had it come from Clinton.

Trump has told visitors in recent weeks that he looked for inspiration to the inaugural addresses of Ronald Reagan and John F. Kennedy. There were echoes of both in his words: Reagan’s blunt rejection of the Washington status quo (“In this present crisis, government is not the solution to our problem; government is the problem”), Kennedy’s call to join a grand national project (“the torch has been passed to a new generation”).

But Trump did not have the uplifting vision with which Reagan ended his speech. And he attached his Kennedy-like promise to send forth a message to his campaign slogan “America First.”

“We will seek friendship and good will with the nations of the world,” he said. “But we do so with the understanding that it is the right of all nations to put their own interests first.”

Trump was as unyielding toward foreign adversaries as he was to domestic ones. He promised to protect America from China and other economic rivals who he said would “ravage” the country by luring away its factories or stealing its jobs. And he pledged what would amount to a clash of civilizations in the fight against Muslim extremism.

The United States, Trump said, would “unite the civilized world against radical Islamic terrorism, which we will eradicate completely from the face of the earth.”

“At the bedrock of our politics,” he concluded, “will be a total allegiance to the United States of America.”

SIGNS ... TRUMP’S OPPONENTS WILL RETURN THE FAVOUR.