At first it sounded like hyperbole, the escalation of a Twitter war. But now it’s clear that Bob Corker’s remarkable New York Times interview—in which the Republican senator described the White House as “adult day care” and warned Trump could start World War III—was an inflection point in the Trump presidency. It 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.”

According to two sources familiar with the conversation, Trump vented to his longtime security chief, Keith Schiller, “I hate everyone in the White House! There are a few exceptions, but I hate them!” (A White House official denies this.) Two senior Republican officials said Chief of Staff John Kelly is miserable in his job and is remaining out of a sense of duty to keep Trump from making some sort of disastrous decision. Today, speculation about Kelly’s future increased after Politico reported that Kelly’s deputy Kirstjen Nielsen is likely to be named Homeland Security Secretary—the theory among some Republicans is that Kelly wanted to give her a soft landing before his departure.

Video: The Stakes are Too High for the Trump Presidency to be Funny

One former official even speculated that Kelly and Secretary of Defense James Mattis have discussed what they would do in the event Trump ordered a nuclear first strike. “Would they tackle him?” the person said. Even Trump’s most loyal backers are sowing public doubts. This morning, The Washington Post quoted longtime Trump friend Tom Barrack saying he has been “shocked” and “stunned” by Trump’s behavior.

While Kelly can’t control Trump’s tweets, he is doing his best to physically sequester the president—much to Trump’s frustration. One major G.O.P. donor told me access to Trump has been cut off, and his outside calls to the White House switchboard aren’t put through to the Oval Office. Earlier this week, I reported on Kelly’s plans to prevent Trump from mingling with guests at Mar-a-Lago later this month. And, according to two sources, Keith Schiller quit last month after Kelly told Schiller he needed permission to speak to the president and wanted written reports of their conversations.

The White House denies these accounts. “The President’s mood is good and his outlook on the agenda is very positive,” an official said.

West Wing aides have also worried about Trump’s public appearances, one Trump adviser told me. The adviser said aides were relieved when Trump declined to agree to appear on the season premiere of 60 Minutes last month. “He’s lost a step. They don’t want him doing adversarial TV interviews,” the adviser explained. Instead, Trump has sat down for friendly conversations with Sean Hannity and Mike Huckabee, whose daughter is Trump’s press secretary. (The White House official says the 60 Minutes interview is being rescheduled.)

Even before Corker’s remarks, some West Wing advisers were worried that Trump’s behavior could cause the Cabinet to take extraordinary Constitutional measures to remove him from office. Several months ago, according to two sources with knowledge of the conversation, former chief strategist Steve Bannon told Trump that the risk to his presidency wasn’t impeachment, but the 25th Amendment—the provision by which a majority of the Cabinet can vote to remove the president. When Bannon mentioned the 25th Amendment, Trump said, “What’s that?” According to a source, Bannon has told people he thinks Trump has only a 30 percent chance of making it the full term.

This post has been updated to clarify the details of the negotiation with 60 Minutes.