President Trump hands a signed "Make America Great Again" hat back to a supporter in Reno, Nev., in August 2017. (Alex Brandon/AP)

Michael Abramowitz is president of Freedom House.

The challenges facing American democracy did not begin with President Trump. But midway through his term, there remains little doubt that his influence is straining core U.S. values, testing the constitutional system’s stability , and undermining democracies and the cause of freedom beyond the nation’s borders.

Through our annual Freedom in the World report, Freedom House has been measuring political rights and civil liberties in every country for nearly 50 years. While our assessments of countries overseas typically command the most attention, we always look inward at the United States as well. As indicated by our latest report, which is being released Tuesday, we have never been more concerned about the health of American democracy.

By global standards, democracy in the United States remains robust, but it has weakened significantly in the past decade, according to our research. Intensifying political polarization, declining economic mobility, the outsize influence of special interests and the diminished influence of fact-based news reporting in favor of bellicose partisan media were all problems afflicting American democracy well before 2017. But Trump’s frequent attacks on essential norms and institutions — such as an independent judiciary, separation of powers, a free press and the legitimacy of elections — threaten to accelerate the decline by wearing down democratic checks and balances.

The grim reality is that Freedom House now ranks the United States well below other large and long-standing democracies, such as France, Germany and Britain.

Many of the United States’ most important institutions have fought hard to maintain democratic standards. The independent media, the judiciary, an energetic civil society, the political opposition and other guardrails of the constitutional system — as well as some conscientious lawmakers and officeholders from Trump’s own party — have checked the president’s worst impulses and mitigated the effects of the administration’s approach.

But the system’s durability is not guaranteed to continue indefinitely. Elsewhere in the world, including Hungary, Venezuela and Turkey, Freedom House has watched democratic institutions gradually succumb to sustained pressure, often after a deceptively slow start.

Since 2016, the United States has suffered declines in the rule of law, the conduct of elections and safeguards against corruption, among other important indicators measured for the Freedom in the World report. Moreover, irresponsible rhetoric and the rejection of democratic constraints on power by political leaders can lead to further restrictions on freedom. Those assaults could intensify if the findings of special counsel Robert S. Mueller III’s investigation implicate the president in wrongdoing.

The stakes in this struggle are high. For all of the claims that the United States has lost influence abroad over the past decade, the reality is that other countries pay close attention to the conduct of the world’s oldest functioning democracy, and it remains irreplaceable as a champion of political rights and civil liberties. The deterioration of U.S. democracy will hasten the current decline in democracy worldwide. Indeed, it has already done so.

The president’s attacks on the judiciary and the media, his resistance to anticorruption constraints and his unfounded claims of voting fraud by the opposition are tactics familiar to foreign autocrats and populist demagogues who seek to subvert checks on their power.

Such leaders take heart from Trump’s bitter feuding with the United States’ traditional democratic allies and his reluctance to uphold the nation’s collective defense treaties, which have helped guarantee international security for decades. The president has refused to advocate American democratic values overseas, and he seems to encourage the forces that oppose them. His frequent praise for some of the world’s worst dictators reinforces this perception.

The effects of his actions are visible around the globe. Cambodian strongman Hun Sen consolidated one-party rule in sham elections last summer after banning the main opposition party and shutting down independent media. He said he shared Trump’s views of journalists, saying, “Donald Trump understands that they are an anarchic group.” Polish President Andrzej Duda, whose party has sought to annihilate judicial independence and assert control over the media, has similarly thanked Trump for fighting “fake news.” Saudi Arabia’s crown prince, Mohammed bin Salman, almost certainly ordered the assassination of a leading journalistic critic, apparently believing that doing so would not rupture relations with the president of the United States. It seems he was correct.

President Ronald Reagan said during his first inaugural address , “As we renew ourselves here in our own land, we will be seen as having greater strength throughout the world. We will again be the exemplar of freedom and a beacon of hope for those who do not now have freedom.” Nearly four decades later, the idea that the United States is such an exemplar is being steadily discredited. It will take years to recover. Americans, their elected officials and both major political parties — along with the independent media and other elements of civil society — urgently need to protect democracy in what is still the world’s most influential country, for their own sake and for the sake of freedom-loving people everywhere.