The United Nations General Assembly, the so-called Super Bowl of diplomacy, was yet another opportunity for Secretary of State Rex Tillerson to take charge, to change the narrative, to squelch the talk that U.N. Ambassador Nikki Haley was soon to take his job.

But, bafflingly, he missed it—if he even wanted it. Along with Haley and National Security Adviser H.R. McMaster, Tillerson took up the mantle of promoting the event on the Sunday morning cable-news circuit, but his performance largely went unnoticed. As diplomats descended on Midtown Tuesday, one top career foreign-service officer—who left the State Department earlier this year—told me that while Tillerson had been “relatively quiet, off-camera” their “first gut instinct was that [Haley] looked like the [secretary of state].”

“He is increasingly not seen as the most authoritative and influential voice on world affairs,” Brett Bruen, a former foreign-service officer who also served as the White House director of global engagement under Barack Obama, told me. “Foreign leaders want to talk to somebody who is not going to only have influence internally . . . it is critical to keep in mind how influential that top diplomat position is for what they do or don’t say publicly.”

By Wednesday night, Tillerson had established even more firmly his position outside of the loop. While speaking with reporters after a closed-door meeting with Iranian officials on the sidelines of U.N.G.A., Tillerson stated that Trump was “still considering” recertifying the Iran nuclear pact—despite the fact that hours earlier the president said he had made up his mind. The secretary tried to recover, adding that while he was aware that Trump made the decision, “I didn’t know he was going to say today he’s made a decision,” and that Trump “has not shared that with anyone externally.” But the exchange exposed Tillerson’s shrinking profile and his glaring disconnect with his boss.

R.C. Hammond, Tillerson’s communications director, dismissed the narrative that the secretary is losing influence with Trump, casting his profile as part of a broader shift in U.S. foreign policy on a number of critical issues, such as new challenges the U.S. faces in the Middle East and the enduring North Korean nuclear threat. “The president continues to task him and ask of him to be America’s lead diplomat, and he continues to do that so we can work on these projects,” Hammond told me, pointing to Chinese President Xi Jinping’s decision to compel Chinese banks to cease conducting business with North Korean businesses as evidence of Tillerson’s effective, back-channel diplomacy. “That is in part a result of the silent or quiet diplomacy that the secretary has put forward over the last several months.” On Friday, Tillerson himself finally pushed back on the Haley rumors. “I think we have a secretary of state currently and I think he is planning to hang around,” he said.

Yet according to more than a half-dozen accounts, Tillerson is an increasingly diminished presence in U.S. foreign policy—and, more surprisingly, he doesn’t seem inordinately concerned by his growing isolation. Described as a “one man show” who has alienated himself from much-needed allies on Capitol Hill, in the White House, and among the career foreign and civil-service officers that make up the agency he heads, the erstwhile ExxonMobil C.E.O. continues to cede foreign policy ground to Jared Kushner and to Haley. The Senate, meanwhile issued a stinging rebuke of Tillerson’s grand scheme to reimagine the sprawling agency along corporate lines. “He does not recognize that the secretary of state needs to be a very big figure and that being a big public figure helps you in Congress, it helps you with other foreign ministers, it helps you with the Cabinet, it helps you with the president,” a former State Department official told me, speaking on condition of anonymity. “You can’t just be an inside player.”