Marco Rubio, Secretary of Everything

Secretary of state. Acting administrator of the U.S. Agency for International Development. Acting archivist for the National Archives and Records Administration. And now interim national security adviser to President Trump.

Like a Christmas tree bedecked with shiny ornaments of every shape and size, Marco Rubio, 53, has accumulated four titles starting with his confirmation as secretary of state on Jan. 20, the same day that Mr. Trump took his oath of office.

It very well could be a record in the modern history of the U.S. government. And it adds to the immigrant success story that is core to the narrative of Mr. Rubio, a former senator from Florida whose father worked as a bartender and mother toiled as a housekeeper after they left Cuba for the United States.

But the proliferation of titles raises questions about whether Mr. Rubio can play any substantial role in the administration if he is juggling all these positions, especially under a president who eschews the traditional workings of government and who has appointed a businessman friend, Steve Witkoff, as a special envoy handling the most sensitive diplomacy.

Mr. Trump announced Mr. Rubio’s newest position in a social media post on Thursday afternoon, a surprise twist in the first big personnel shake-up of this administration. The president had just ousted Michael Waltz from the White House national security adviser job as well as Mr. Waltz’s deputy, Alex Wong. In the same post, Mr. Trump said Mr. Waltz would now be his nominee to be ambassador to the United Nations.

Mr. Rubio’s appointment to yet another job — as if he were cloned in a B-grade sci-fi movie — was so sudden that Tammy Bruce, the State Department spokeswoman, learned about it when a reporter read Mr. Trump’s social media post to her during a regular televised news conference.

“Yeah, so that is the miracle of modern technology and social media,” Ms. Bruce said. “So that is an exciting moment here.”

Scrambling to try to explain the events unfolding in real time, Ms. Bruce said: “We’ve seen him be at the White House several times a week, his close working relationship day to day with the president. They clearly have been in an environment where they’ve gotten to know each other very well.”

The fact that Mr. Rubio now leads four bodies is a sign not only of the trust placed in him by Mr. Trump, but also of the close relationship he has with Susie Wiles, the veteran political operative who is Mr. Trump’s chief of staff.

Of course, having four jobs also raises more practical issues: Does Mr. Rubio get a pay bump? Will he have time to hop around the globe to do diplomacy? How will he delegate his duties?

There are precedents — sort of. From 1973-75, Henry Kissinger held two of Mr. Rubio’s jobs, secretary of state and national security adviser, in an experiment that was considered a failure. In the current Trump administration, two officials, Kash Patel, the F.B.I. director, and Daniel Driscoll, the Army secretary, have both been interim head of the Bureau of Alcohol, Tobacco, Firearms and Explosives while also serving in their more prominent posts.

But it might be more relevant to look outside the United States for examples. Xi Jinping, China’s leader, is general secretary of the Communist Party, president of China and chairman of the Central Military Commission — still one job short of Mr. Rubio’s tally.

The Senate unanimously confirmed Mr. Rubio to be secretary of state. But he entered the other jobs under controversial circumstances. Mr. Trump fired the head archivist, Colleen Shogan, in early February in an apparent act of retribution against the National Archives and Records Administration. Leaders of the agency had raised concerns about Mr. Trump’s holding onto boxes of classified documents at his home in Florida after he left office in 2021, though Ms. Shogan was not involved in that episode.

Four days before Ms. Shogan’s firing, Mr. Rubio announced he was the acting administrator for U.S.A.I.D., as Elon Musk, the billionaire adviser to Mr. Trump, and Pete Marocco, a political appointee in the State Department, were gutting the agency. Mr. Marocco and members of Mr. Musk’s government-slashing task force did the daily work of reducing the agency to a husk, cutting contracts and firing thousands of employees, but Mr. Rubio signed off on the moves.

Mr. Rubio is moving the remnants of the agency into the State Department. Last week, he issued a chart on his planned department reorganization that shows him keeping the title of U.S.A.I.D. administrator.

Even before Mr. Trump appointed the top U.S. diplomat/archivist/aid agency administrator to be interim national security adviser, some analysts were pointing out the problems with Mr. Rubio holding all these positions.

“Occupying two (or in Rubio’s case, three) roles at once is never ideal — directing government agencies and programs is a significant task that demands attention and focus,” said a post on the site of Citizens for Responsibility and Ethics in Washington, a government watchdog group, in March. “But Rubio’s current positions are uniquely concerning.”

The writer, Gabriella Cantor, pointed out the obvious conflict of interest: The archivist is supposed to ensure that other federal agencies, including the two Mr. Rubio is also leading, preserve records. Now, with the addition of the White House National Security Council, that becomes thornier.

As for the question of Mr. Rubio’s salary (or salaries), the State Department did not reply when asked on Thursday afternoon.

Michael Crowley contributed reporting.