Democracy is a bit like a sand castle. It takes a long time to build, even longer to perfect grain by grain, and almost no time at all for it to be washed away by a wave of authoritarianism.

After six months in office, it has become clear that President Donald Trump is a threat to American democracy. And if he continues at his pace, it’s going to take a lot of meticulous effort to rebuild the damage once he leaves office.

This isn’t a Republican or Democrat issue. A President Rubio or a President Romney would not be threats to democratic principles. It is unique to Trump.

But the red lights of democratic decay are flashing. Trump’s most authoritarian impulses are new to America — including his dire rhetoric on North Korea — but they are straight from the greatest hits of other authoritarian-minded rulers around the globe.

He’s following in the footsteps of despots by trying to blur the line between fact and falsehood. Any independent narrative that challenges his preferred storyline is “fake.” He said all negative polls are fake; his administration called the independent, nonpartisan Congressional Budget Office “little more than fake news.” Day by day, Trump seeks to become the sole arbiter of truth to his core supporters — even though he has made hundreds of demonstrably false statements, an unprecedented pattern of dishonesty in government.

Like President Recep Tayyip Erdogan of Turkey, Trump savages the media at every opportunity. Sure, the media sometimes gets it wrong and news outlets are everyone’s favorite punching bag. But a widely respected free press is also integral to the functioning of democratic government — a system that relies, at its core, on informed consent of the governed.

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Like the late dictator of Uzbekistan, Islam Karimov, Trump placed his unqualified daughter Ivanka Trump at the highest echelons of power in the government and has allowed her to represent the country on the international stage. Her husband, Jared Kushner, has been tasked with solving just about every intractable problem — from restructuring the federal government to bringing peace to the Middle East. Neither Jared nor Ivanka would even be considered for a senior position in any other presidential administration. They are there solely because of their family ties. Nepotism is a hallmark of authoritarian societies and a blight on democratic ones.

Like President Rodrigo Duterte of the Philippines, Trump sees himself as above the law. He admitted to firing former FBI Director James Comey because Comey was investigating Russia’s ties to the election and Trump’s inner circle. Trump publicly attacked Attorney General Jeff Sessions for following federal guidelines for recusal — effectively hammering Sessions because he did not obstruct justice. And Trump has openly flirted with firing Special Counsel Bob Mueller, or pardoning himself and his closest associates for potential crimes. Democracy relies on rule of law. Trump seems to view it as a pesky annoyance.

Then there’s his routine ethics violations; his calls to jail his defeated political foes; his bogus claims about illegal voting aimed at casting aspersions on election integrity; his politicization of independent government institutions; and his use of public office to promote private business holdings.

Trump is already damaging American democracy. Tens of millions of Americans will believe that mainstream news outlets are “fake news” for the foreseeable future. By a margin of 45 percent to 20 percent, Republicans support closing down “biased” media outlets. Trump has ushered a worrying acceptance of authoritarian impulses into the political mainstream.

So, how do we protect our democratic sand castle? How do we shore it up?

First, speak out when democratic principles are violated with the same fervor that you would for a proposed law change. The backlash against TrumpCare was enormous. The backlash against Trump’s violations of democratic norms has been invisible by comparison. That’s a mistake, because health policy is far easier to reverse than an eroded democracy is to rebuild. Call Congress. Ask your representatives to band together across party lines to protect democratic principles. Make clear that you’re willing to stake future votes on it.

Second, speak to people you know across party lines regarding democratic principles. Debates about tax policy should divide people in a democratic society. The core principles of democracy should not. It may sound trivial, but we’ve taken that common ground for granted for too long — and that is why it is now vulnerable.

Third, protest, debate, discuss, and make sure you’re informed from reliable sources. Democracy is not a spectator sport. Trump could actually end up reinvigorating American democracy if the backlash against his authoritarian impulses sparks a resurgence of citizen participation in government.

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Fourth, and finally, urge your state officials to address gerrymandering and uncompetitive districting. Most elections for the House of Representatives are foregone conclusions before ballots are even printed. Uncompetitive districts reward extremism and punish compromise. We need structural reform to ensure that common sense prevails over partisan absolutism.

Democracy is worth protecting. But nobody is going to protect it for us. It’s up to every one of us whether the meticulously built great American experiment stands firm, or slowly gets washed away by the Trump wave.

Brian Klaas, the author of “The Despot’s Accomplice: How the West is Aiding & Abetting the Decline of Democracy,” is a fellow in comparative politics at the London School of Economics.