“I always said that it was going to take awhile for Donald Trump to adjust as president,” said Christopher Ruddy, the chief executive of Newsmax Media and an old friend of the president’s. In business, he said, Mr. Trump relied on a small circle of colleagues and a management style that amounted to “trial and error — the strongest survived, the weak died.”

Mr. Ruddy insisted that Mr. Trump was finding his groove in the Oval Office. But his subordinates are faring less well. With an erratic boss and little in the way of a coherent legislative agenda, they are consumed by infighting, fears of their legal exposure and an ambient sense that the White House is spinning out of control.

Mr. Trump is isolated and angry, as well, according to other friends and aides, as he carries on a bitter feud with his attorney general and watches members of his family clash with a chief of staff he recruited to restore a semblance of order — all against the darkening shadow of an investigation of his ties to Russia.

The combined effect is taking a toll.

Mr. Trump’s instinct during these moments is to return to the populist themes that carried him to the White House, which is why his trade announcement is hardly surprising. Mr. Trump has few fixed views on any issue, but he has been consistent on his antipathy for free trade since the 1980s, when he took out newspaper ads warning about American deficits with Japan — a concern that has shifted to China in recent years.

“The W.T.O. has been a disaster for this country,” Mr. Trump said Thursday, asserting that China’s economic rise coincided with its entry into the World Trade Organization. “It has been great for China and terrible for the United States, and great for other countries.”

But a president who has long tried to impose his version of reality on the world is finding the limits of that strategy. Without Mr. Porter playing a stopgap role on trade, the debate has been marked by a lack of focus on policy and planning, according to several aides.

Morale in the West Wing has sunk to a new low, these people said. In private conversations, Mr. Trump lashes out regularly at Attorney General Jeff Sessions with a vitriol that stuns members of his staff. Some longtime advisers said that Mr. Trump regards Mr. Sessions’s decision to recuse himself from the Russia investigation as the “original sin,” which the president thinks has left him exposed.