He swooped into politics, he declared, to subvert the powerful and rescue those who cannot defend themselves. “Nobody knows the system better than me, which is why I alone can fix it.”

To Trump’s faithful, those words were a rallying cry. But his critics heard something far more menacing in them: a dangerously authoritarian vision of the presidency — one that would crop up time and again as he talked about overruling generals, disregarding international law, ordering soldiers to commit war crimes, jailing his opponent.

Trump has no experience in politics; he’s never previously run for office or held a government position. So perhaps he was unaware that one of the hallmarks of the American system of government is that the president’s power to “fix” things unilaterally is constrained by an array of strong institutions — including the courts, the media, the permanent federal bureaucracy and Congress. Combined, they provide an essential defense against an imperial presidency.

Yet in his first weeks at the White House, President Trump has already sought to undermine many of those institutions. Those that have displayed the temerity to throw some hurdle in the way of a Trump objective have quickly felt the heat.

Consider Trump’s feud with the courts.

He has repeatedly questioned the impartiality and the motives of judges. For example, he attacked the jurists who ruled against his order excluding travelers from seven majority Muslim nations, calling one a “so-called judge” and later tweeting:

Just cannot believe a judge would put our country in such peril. If something happens blame him and court system. People pouring in. Bad!

— Donald J. Trump (@realDonaldTrump) February 5, 2017

It’s nothing new for presidents to disagree with court decisions. But Trump’s direct, personal attacks on judges’ integrity and on the legitimacy of the judicial system itself — and his irresponsible suggestion that the judiciary should be blamed for future terrorist attacks — go farther. They aim to undermine public faith in the third branch of government.

The courts are the last line of defense for the Constitution and the rule of law; that’s what makes them such a powerful buffer against an authoritarian leader. The president of the United States should understand that and respect it.

Other institutions under attack include:

1. The electoral process. Faced with certified election results showing that Hillary Clinton outpolled him by nearly 3 million votes, Trump repeated the unsubstantiated — and likely crackpot — assertion that Clinton’s supporters had duped local polling places with millions of fraudulent votes. In a democracy, the right to vote is the one check that the people themselves hold against their leaders; sowing distrust in elections is the kind of thing leaders do when they don’t want their power checked.

2. The intelligence community. After reports emerged that the Central Intelligence Agency believed Russia had tried to help Trump win, the president-elect’s transition team responded: “These are the same people that said Saddam Hussein had weapons of mass destruction.” It was a snarky, dismissive, undermining response — and the administration has continued to belittle the intelligence community and question its motives since then, while also leaking stories about possibly paring and restructuring its ranks. It is bizarre to watch Trump continue to tussle publicly with this particular part of the government, whose leaders he himself has appointed, as if he were still an outsider candidate raging against the machine. It’s unnerving too, given the intelligence services’ crucial role in protecting the country against hidden risks, assisting the U.S. military and helping inform Trump’s decisions.

3. The media. Trump has blistered the mainstream media for reporting that has cast him in a poor light, saying outlets concocted narratives based on nonexistent anonymous sources. In February he said that the “fake news” media will “never represent the people,” adding ominously: “And we’re going to do something about it.” His goal seems to be to defang the media watchdog by making the public doubt any coverage that accuses Trump of blundering or abusing his power.

4. Federal agencies. In addition to calling for agency budgets to be chopped by up to 30%, Trump appointed a string of Cabinet secretaries who were hostile to much of their agencies’ missions and the laws they’re responsible for enforcing. He has also proposed deep cuts in federal research programs, particularly in those related to climate change. It’s easier to argue that climate change isn’t real when you’re no longer collecting the data that documents it.

In a way, Trump represents a culmination of trends that have been years in the making.

Conservative talk radio hosts have long blasted federal judges as “activists” and regulators as meddlers in the economy, while advancing the myth of rampant election fraud. And gridlock in Washington has led previous presidents to try new ways to circumvent the checks on their power — witness President George W. Bush’s use of signing statements to invalidate parts of bills Congress passed, and President Obama’s aggressive use of executive orders when lawmakers balked at his proposals.

What’s uniquely threatening about Trump’s approach, though, is how many fronts he’s opened in this struggle for power and the vehemence with which he seeks to undermine the institutions that don’t go along.

It’s one thing to complain about a judicial decision or to argue for less regulation, but to the extent that Trump weakens public trust in essential institutions like the courts and the media, he undermines faith in democracy and in the system and processes that make it work.

He sees himself as not merely a force for change, but as a wrecking ball.

Trump betrays no sense for the president’s place among the myriad of institutions in the continuum of governance. He seems willing to violate long-established political norms without a second thought, and he cavalierly rejects the civility and deference that allow the system to run smoothly. He sees himself as not merely a force for change, but as a wrecking ball.

Will Congress act as a check on Trump’s worst impulses as he moves forward? One test is the House and Senate intelligence committees’ investigation into Russia’s meddling in the presidential election; lawmakers need to muster the courage to follow the trail wherever it leads. Can the courts stand up to Trump? Already, several federal judges have issued rulings against the president’s travel ban. And although Trump has railed against the decisions, he has obeyed them.

None of these institutions are eager to cede authority to the White House and they won’t do so without a fight. It would be unrealistic to suggest that America’s most basic democratic institutions are in imminent jeopardy.