Americans have sharply different views about what government should do, whether on abortion, guns, immigration or any number of hot-button issues. But we broadly agree about how government should go about resolving our differences.

This distinction – between what we disagree about and how we settle those disagreements – is crucial. As long as we continue to agree on the how, the processes and institutions of governance, we can accept what is decided even if we’re unhappy about it.

To state it another way, Americans don’t always like what government does but they overwhelmingly support the American system of government. They want to improve it, not destroy it.

Enter Donald Trump, who has turned this how-what distinction on its head. In order to get what he wants, Trump rides roughshod over how we decide. He is the great destroyer.

This is the most profound challenge to our system of government since Richard Nixon went rogue

His directive to his lapdog attorney general, William Barr, to find evidence of “treason” against specific people who investigated him threatens the neutrality of our entire system of justice, as does Barr’s assertion of “no limit” on the president’s authority to direct law enforcement investigations, including those he’s personally interested in.

Trump’s blanket refusal to comply with House subpoenas and investigations flies in the face of how Congress is supposed to oversee the executive branch.

Trump’s 2016 campaign aides’ eagerness to get dirt on his opponent from Russia, and Trump’s efforts to suppress evidence about those dealings, undermine how the American electoral system is supposed to run.

Trump’s declaration of a national emergency to justify using funds to build his wall that Congress refused to appropriate, obliterates how spending decisions are supposed to be made.

Trump’s angry references to “Obama judges” who rule against him calls into question the independence and legitimacy of the judiciary.

Trump’s hints at violence if he doesn’t get his way – such as his March insinuation that “I have the support of the police, the support of the military, the support of the Bikers for Trump – I have the tough people, but they don’t play it tough – until they go to a certain point, and then it would be very bad, very bad” – threatens the democratic foundations of our society.

Taken as a whole, these attacks on our basic agreement about how to resolve our disagreements constitute the most profound challenge to our system of government since Richard Nixon went rogue.

Thankfully, most Americans oppose them. Even with record low unemployment, Trump’s approval ratings remain in the cellar. About 35%, Trump’s hardcore base, continue to stick by him, but independents and even some Republicans are deserting him in droves.

Although impeachment is the appropriate remedy for a president who assaults our system of government, most of the public opposes this move as well. I think that’s because in these especially perilous times, impeachment threatens to pull the system further apart, possibly to the breaking point.

Importantly, the courts are stepping up.

On Monday, Judge Amit Mehta ruled against Trump, saying “lawmakers should get documents they have subpoenaed”.

On Wednesday, Judge Edgardo Ramos refused to block subpoenas from the House financial services and intelligence committees for Trump records from Deutsche Bank and Capital One.

On Friday, Judge Haywood Gilliam granted a preliminary injunction blocking Trump’s use of $1bn from the Department of Defense for building his wall.

These decisions are significant not just because they are victories for House Democrats, but because they confirm that the American system of government is still working, Trump notwithstanding.

Richard Nixon approaches the foul line. Photograph: Bettmann/Bettmann Archive

He may yet succeed in running out the clock – dragging out appeals through election day. But every court decision that adds legitimacy to the processes and institutions Trump has been attacking makes him look more like the dangerous wrecking ball he is.

Over the past several months I have heard some on the left talk about meeting fire with fire, if and when Democrats regain the White House and Senate.

To counteract Trump’s (and let’s not forget Mitch McConnell’s) malfeasance, they want to alter the system in ways that favor their side – expanding the number of supreme court justices, for example, or eliminating the Senate filibuster, or dividing California into three states, each with its own two senators. And so on.

This would be a mistake. Americans want to preserve our agreement over how to resolve our disagreements, and are witnessing the threat Trump and the Republicans present to it.

The Democratic party should dedicate itself to protecting that agreement. This is the hallmark of a true governing party. Trump and the Republicans, by contrast, are digging themselves ever more deeply into a hole from which they may never emerge.