Republican presidents and presidential candidates have used their leadership at critical moments to set a tone for society to live up to. Mr. Reagan faced down totalitarianism in the 1980s, appointed the first woman to the Supreme Court and worked with Democrats on bipartisan tax and immigration reforms. George H.W. Bush signed the Americans With Disabilities Act and decisively defended an ally, Kuwait, against Iraqi aggression. George W. Bush, for all his failures after Sept. 11, did not stoke hate against or demonize Muslims or Islam.

As a candidate during the 2008 race, Mr. McCain spoke out when his fellow conservatives spread lies about his opponent, Barack Obama. Mr. Romney was willing to sacrifice his standing and influence in the party he once represented as a presidential nominee, by boldly calling out Mr. Trump’s failings and voting for his removal from office.

These acts of leadership are what it means to put country first, to think beyond oneself.

Mr. Trump has demonstrated contempt for these American ideals. He admires autocrats, from Viktor Orban to Vladimir Putin to Kim Jong-un. He believes in the strongman model of power — a leader who makes things happen by demanding it, compelling agreement through force of will or personality. In reality, a strongman rules through fear and the unprincipled use of political might for self-serving ends, imposing poorly conceived policies that smother innovation, entrepreneurship, ideas and hope.

During his four years in office, Mr. Trump tried to govern the United States as a strongman would, issuing orders or making decrees on Twitter. He announced sudden changes in policy — on who can serve in the military, on trade policy, on how the United States deals with North Korea or Russia — without consulting experts on his staff about how these changes would affect America. Indeed, nowhere did he put his political or personal interests above the national interest more tragically than during the pandemic, when he faked his way through a crisis by touting conspiracy theories and pseudoscience while ignoring the advice of his own experts and resisting basic safety measures that would have saved lives.

He took a similar approach to America’s strategic relationships abroad. Mr. Trump lost the trust of America’s longstanding allies, especially in NATO, leaving Europe less secure and emboldening the far right and authoritarian leaders in Europe, Latin America and Asia. He pulled out of the Iran nuclear deal, leaving that country, already a threat to the world, more dangerous, thanks to a revived program that has achieved near-weapons-grade uranium.

In a second term, his willingness to appease Mr. Putin would leave Ukraine’s future as a democratic and independent country in doubt. Mr. Trump implies that he could single-handedly end the catastrophic war in Gaza but has no real plan. He has suggested that in a second term he’d increase tariffs on Chinese goods to 60 percent or higher and that he would put a 10 percent tariff on all imported goods, moves that would raise prices for American consumers and reduce innovation by allowing U.S. industries to rely on protectionism instead.

The worst of the Trump administration’s policies were often blocked by Congress, by court challenges and by the objections of honorable public servants who stepped in to thwart his demands when they were irresponsible or did not follow the law. When Mr. Trump wanted an end to Obamacare, a single Republican senator, Mr. McCain, saved it, preserving health care for millions of Americans. Mr. Trump demanded that James Comey, his F.B.I. director, pledge loyalty to him and end an investigation into a political ally; Mr. Comey refused. Scientists and public health officials called out and corrected his misinformation about climate science and Covid. The Supreme Court sided against the Trump administration more times than any other president since at least Franklin D. Roosevelt.

A second Trump administration would be different. He intends to fill his administration with sycophants, those who have shown themselves willing to obey Mr. Trump’s demands or those who lack the strength to stand up to him. He wants to remove those who would be obstacles to his agenda, by enacting an order to make it easier to fire civil servants and replace them with those more loyal to him.

This means not only that Americans would lose the benefit of their expertise but also that America would be governed in a climate of fear, in which government employees must serve the interests of the president rather than the public. All cabinet secretaries follow a president’s lead, but Mr. Trump envisions a nation in which public service as Americans understand it would cease to exist — where individual civil servants and departments could no longer make independent decisions and where research by scientists and public health experts and investigations by the Justice Department and others in federal law enforcement would be more malleable to the demands of the White House.

Another term under Mr. Trump’s leadership would risk doing permanent damage to our government. As Mr. Comey, a longtime Republican, wrote in a 2019 guest essay for Times Opinion, “Accomplished people lacking inner strength can’t resist the compromises necessary to survive Mr. Trump and that adds up to something they will never recover from.” Very few who serve under him can avoid this fate “because Mr. Trump eats your soul in small bites,” Mr. Comey wrote. “Of course, to stay, you must be seen as on his team, so you make further compromises. You use his language, praise his leadership, tout his commitment to values. And then you are lost. He has eaten your soul.” America will get nowhere with a strongman. It needs a strong leader.