With each day, President Trump offers fresh proof that he is failing the office that Americans entrusted to him. The rolling disaster of his presidency accelerated downhill last week with a news conference on Tuesday at which he seemed determined to sow racial strife in a nation desperate for a unifying vision.

Since the 1930s it has not typically been a challenge for an American leader to denounce Nazism. But there is nothing typical about this president; urged by some of his advisers and family members to summon the majesty and moral authority of the presidency to heal the wounds of last weekend’s neo-Nazi violence in Charlottesville, to put the good of the country before personal pique, he chose instead to deliver a defense of white supremacists that raised as never before profound doubts about his moral compass, his grasp of the obligations of his office and his fitness to occupy it.

This, in essence, is where we are now: a nation led by a prince of discord who seems divorced from decency and common sense. The alarm bells were loud and swift. Five members of the Joint Chiefs of Staff delivered a rare rebuke, condemning race-based extremism in the military and the nation. Foreign leaders, from Secretary General António Guterres of the United Nations to Prime Minister Theresa May of Britain, condemned intolerance and a failure of leadership in the White House.

Of all the many complaints and condemnations, the strongest came from Mr. Trump’s putative allies in the business community, a glittering who’s who of financial and corporate leaders who began resigning from two White House advisory councils early last week, ultimately forcing the president to dissolve both panels in order to spare himself the humiliation of further corporate desertions. The White House ultimately abandoned a third advisory council, on infrastructure, an area where Mr. Trump had hoped to fulfill at least one of his campaign promises to create jobs.