On the Acela Express from Washington to Boston, I am searching my hopper of words for one that describes the feeling of watching on television Donald Trump’s press conference in Florida. I am, as it were, dumbfounded by the braggart.

Watching Trump is like watching one of nature’s lethal creatures, say a mamba or a crocodile. One wonders at the deadly speed of the snake, coiled and ready to strike its victim: a thing of beauty in its lethality, mesmerizing; or the evil certainty of the croc, always ready to go from seeming lethargy to lighting assault, if the unwary should seek to share the river bank.

So with the man who would be president: He has the dubious appeal of a bombaster, as he trashes people who have given their lives to public service with success, like Vice President Joe Biden and Sen. John McCain, R-Ariz. Men and women who have earned high marks in the esteem of their professions and the nation.

They are fools, losers, stupid and worse, in the profane stream of venom that passes for campaigning from Trump. He is a man who has so little respect for others that you wonder what he does respect, besides his own money (which he refers to frequently) and foreign strongmen, like Russia’s Vladimir Putin.

Name-calling is part of the political dialogue, but this is something other again, this Niagara Falls of abuse, of disrespect of verbal infamy; this sick, sick performance of denigrating the United States so he can save it. It is a risible attack on Americans who have built America. It also is an attack on America, and an insight into Trump’s ignorance of the world. By the way, Mr. Trump, America is still the world’s most powerful country.

Trump calls everyone he encounters names. He also calls them liars; his opponents in the primaries were liars, as is his Democratic opponent now. He calls the media “scum.”

The big lies, though, are Trump lies. He is a fairground barker, telling people anything to get them into his tattered tent.

The United States is not despised in the world: We are admired. The economy is not a disaster: It has been growing to the envy of other advanced economies.

America is great right now, today. There are problems here in social equality and other things, and huge problems in the Middle East — some, but not all, could be blamed on policy under the former and current presidents. The world still looks to America to protect, to invent, and to do the right thing.

Trump, who finds nothing good in anyone in public life and nothing good in public policy, has given us no idea of how he would govern and whom he would rely upon to bring about the Age of Trump. All he has released is a list of conservative judges from whom he will appoint Supreme Court nominees.

When it comes to policy, all we know is that he is going to build a wall across the southern frontier, abrogate a lot of treaties, engage in trade wars, leave Europe open to Russian aggression, and extract money for his schemes from our allies and friends.

Yet, sitting behind me on this train, a woman has been praising Trump to her two traveling companions, and only stops to call someone on her cell phone and further praise him. Since biblical times, serpents have been a source of fascination. The woman behind me would follow the political version into the White House.