But the shield has grown thinner. The causes include revelations from multiple investigations involving Trump and Russia, chaos and incompetence in the White House, and public attacks on Republicans including Senate Majority Leader Mitch McConnell.

“The personal disgust for Trump within the Senate is really remarkable,” a top GOP strategist told me last week.

Now the president’s refusal to condemn the “Unite the Right” gathering in Charlottesville, Virginia, which included the former Klan leader Duke, has begun pulling private disdain into the open.

The more obscure the president’s actions, the likelier Republican leaders have been to remain quiet for fear of antagonizing his core supporters. But the graphic, deadly events this past weekend, and the president’s response to them, threaten his party with the broader electorate that grows more diverse and more tolerant with every passing year.

Trump cast white supremacists and neo-Nazis carrying torches onto the University of Virginia campus as morally equivalent to counter-protesters advocating racial equality. His stance — a purposeful choice by a president who relishes singling out so many others for criticism — places him at odds with the values of the nation he was elected to serve.

That raises risks for elected officials who stand with Trump at a moment of legal, as well as political, jeopardy. It further complicates prospects for the Republican agenda on tax cuts, health care and other issues. It increases the possibility that Trump’s presidency itself will be cut short.