The announcement of Anton’s departure coincides with that of McMaster, whose last day was Friday, and with the arrival of John Bolton | Mandel Ngan/AFP via Getty Images Trump’s top national security spokesman to leave White House Michael Anton spent the majority of his tenure serving as spokesman for Michael Flynn’s replacement, H.R. McMaster.

National Security Council spokesman Michael Anton said Sunday that he plans to leave the White House — a move that will leave President Donald Trump without one of the earliest and sharpest defenders of his “America First" foreign policy.

Though Trump’s first national security adviser, Michael Flynn, brought Anton into the administration, he spent the majority of his tenure serving as spokesman for Flynn’s replacement, H.R. McMaster.

Anton said he plans join Hillsdale College’s Kirby Center, the conservative school’s Washington, D.C. outpost, as a writer and lecturer. "I will be forever grateful to President Trump for the opportunity to serve my country and implement his agenda,” he said.

Before joining the Trump administration, Anton had become a controversial figure during the 2016 campaign for his attempt to make the case for Trump’s candidacy. In a pseudonymous essay, “The Flight 93 Election,” he made a highbrow version of Trump’s attack on the Republican establishment, calling conservative intellectuals wilted and outmoded, and praised Trump for connecting the issues of trade, immigration and foreign policy.

Writers affiliated with the Claremont Institute, the California think tank that published Anton’s essay, are among the small coterie of right-leaning intellectuals who have continued to defend the president.

The announcement of Anton’s departure coincides with that of McMaster, whose last day was Friday, and with the arrival of John Bolton, whose first day as national security adviser is Monday. Though Anton has not yet determined when his last day will be, he is expected to leave the White House in the coming weeks.

Inside the White House, Anton, the author of a book about about men’s style, was the rare egghead who managed not to drive the president crazy — and he played a key role weathering McMaster’s testy relationship with the president.

Trump has “nothing but good things to say” about him, said White House Press Secretary Sarah Huckabee Sanders.

“Michael is one of the smartest and most talented individuals I’ve ever worked with — not to mention an amazing chef,” said Sanders, who called him a “true friend.”

“The education I received and the friends I made are — apart from my family and my country — the most cherished things in my life. I am delighted to be returning to my first love and second family,” Anton said, referring to Hillsdale College and the Claremont Institute.

"I have known Michael for just about his entire adult life. His devotion to learning, his love of his country, and his talents of thinking, talking, and writing will make him a valuable colleague. We are proud to welcome him to the Kirby Center,” Hillsdale College President Larry Arnn said.