[Corker’s comments] brought into the open what several people close to the president have recently told me in private: that Trump is “unstable,” “losing a step,” and “unraveling.”

The conversation among some of the president’s longtime confidantes, along with the character of some of the leaks emerging from the White House has shifted. There’s a new level of concern. NBC News published a report that Trump shocked his national security team when he called for a nearly tenfold increase in the country’s nuclear arsenal during a briefing this summer. One Trump adviser confirmed to me it was after this meeting disbanded that Secretary of State Rex Tillerson called Trump a “moron.”

In recent days, I spoke with a half dozen prominent Republicans and Trump advisers, and they all describe a White House in crisis as advisers struggle to contain a president who seems to be increasingly unfocused and consumed by dark moods. Trump’s ire is being fueled by his stalled legislative agenda and, to a surprising degree, by his decision last month to back the losing candidate Luther Strange in the Alabama Republican primary. “Alabama was a huge blow to his psyche,” a person close to Trump said. “He saw the cult of personality was broken.”