Those who have shut their eyes, turned their backs and held their noses for the past two years will not go easily into battle with Mr. Trump. No matter the damage he has done to party or country, they have shown no discernible backbone. While Mr. Leonhardt’s heart is in the right place, I fear that his head may unfortunately be in the clouds.

Robert S. Nussbaum

Fort Lee, N.J.

To the Editor:

David Leonhardt has written the most articulate, well-documented and soundly crafted argument for the removal of Donald Trump from the presidency. This article should be printed and mass distributed all over America, much as Thomas Paine’s “Common Sense” once was. I wasted no time sending it to my members of Congress.

Joyce Grater

Pittsburgh

To the Editor:

Should David Leonhardt’s powerful, comprehensive indictment of President Trump not be enough to persuade Republicans in Congress that he must be removed from office, I suggest they ask themselves these questions. Would they ever put their children on a plane piloted by someone with little previous flight experience, someone who had refused to read the plane’s instruction manuals, someone who had just locked his co-pilots out of the cockpit?

Would they be comfortable if he had said in recent weeks that he felt at “war every day,” had seemed to be more and more suspicious of those around him, including, perhaps, even members of his own family, and had a history of hair-trigger rage against those who defied him? And how would they feel if he had begun to make increasingly rash and dangerous decisions?

The terrifying truth is that all of our children, and all of us, Republicans and Democrats alike, are already on that plane. And as Mr. Leonhardt urgently warns, Republicans had better figure out soon what they are going to do about it.

Eric Chivian

Boston

The writer, a physician, is a former assistant clinical professor of psychiatry at Harvard Medical School.

To the Editor:

While I agreed with much of David Leonhardt’s article, it saddened me to read this part: “The biggest risk may be that an external emergency — a war, a terrorist attack, a financial crisis, an immense natural disaster — will arise. By then, it will be too late to pretend that he is anything other than manifestly unfit to lead .”