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As President Trump waved goodbye to former President Obama’s chopper from the steps of the Capitol Friday, the transition of power to the Trump Presidency was technically complete. Behind the pageantry of the inauguration, however, a skeleton crew of Obama appointees and career bureaucrats quietly ensured that the United States government continued to function.

So far President Trump has nominated appointees to 20 of the 21 Cabinet positions, but only two have been confirmed — both Secretary of Defense James Mattis and DHS Secretary John Kelly were approved by the Senate Friday evening. Hundreds of other positions requiring Senate confirmation are still vacant, and the day-to-day functions of government are being carried out by a series of “acting” secretaries and career government employees.

In total, as of Friday evening there were 688 executive-branch positions requiring Senate-approval that the Trump Administration needed to fill, according to the Partnership for Public Service. President Trump has nominated successors to 28 of those roles.

When President Obama took office in 2009, seven Cabinet members were confirmed on Inauguration Day: six new appointees, and Secretary of Defense Bob Gates, who was retained from the Bush administration.

It’s not unusual for Cabinet roles to be filled months after Inauguration Day. Obama’s Secretary of Commerce Gary Locke wasn’t confirmed until March 24, and his Secretary of Health and Human Services, Kathleen Sebelius, another month after that.

The last president to have no major cabinet members confirmed on his first day in office was President George H. W. Bush 28 years ago, who was coming into office on the heels of another GOP administration and decided to keep two of President Reagan’s appointees.

Holdovers from the Obama Administration and civil bureaucrats will manage the daily workings of government as the new Trump Administration works to fill these roles in the upcoming weeks. Exactly how do the departments keep functioning? Some details follow for a handful of Cabinet level agencies.

Department of State

Secretary of State John Kerry left the State Department building Thursday for the last time as the nation's lead diplomat.

As of 12:01 a.m. on Friday, Tom Shannon, formerly the Under Secretary of State for Political Affairs, is acting Secretary of State. Shannon will remain acting Secretary until President Donald Trump's nominee — former ExxonMobil CEO Rex Tillerson — is confirmed.

The Senate Foreign Relations Committee is expected to vote late Monday afternoon as to whether to approve Tillerson.

U.S. embassies around the world are going through similar transitions. Politically appointed ambassadors are departing. Before the Trump appointees arrive, a second-in-command called the deputy chief of mission serves as acting ambassador. In a departure with tradition, The Trump administration did not allow any political appointees to remain past Inauguration Day.

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Politically appointed ambassadors currently represent just over 30 percent of the 188 ambassadorial positions and include posts in Afghanistan, China, Israel, and Saudi Arabia. Career ambassadors, leading almost 70 percent of U.S. embassies, will remain in their positions.

“For those embassies who will not have an ambassador in place as of noon tomorrow, work will go on. In whatever form it has gone on today, it will go on tomorrow.” State Department Spokesperson John Kirby assured Thursday. “Bilateral relations will continue. And our deputy chiefs of mission will represent fairly and appropriately the United States interest.”

U.S. representation to NATO and the United Nations are also politically appointed positions. President Trump has nominated South Carolina Governor Nikki Haley as ambassador to the UN.

Senate Foreign Relations Committee Chairman Bob Corker said this week that he hopes the committee will be able to vote on Haley’s confirmation at the same time as Tillerson’s.

Department of Defense

Secretary of Defense Ash Carter departed the Pentagon for his final time as secretary at 3:30 p.m. Thursday afternoon. Pentagon tradition dictated that Carter be “clapped out” by employees who lined the halls and applauded as he walked past.

Defense officials said he turned in his badge and Blackberry and completed the turnover before he left.

Despite the fact that he was legally secretary until Donald Trump was sworn in as President, Carter relinquished his responsibilities to Deputy Secretary Robert Work when he left the Pentagon.

Work became acting secretary at 12:01 p.m. today, but before he assumed his new role, he laid out a detailed plan for nearly every leadership position in the Department of Defense.

Work released a memo Thursday afternoon naming the career civilian employees designated as “Acting” or “Performing the Duties of.”

Performing the duties of undersecretary of defense for policy, one of the most powerful civilian roles in the Pentagon, is career senior executive Theresa Whelan.

Work designated acting secretaries for every service as well, including the Army Comptroller Robert Speer who is now acting secretary for the Army, and the head of U.S. Navy acquisition, Sean Stackley, taking over as acting secretary for the Navy.

Gen. James Mattis has now been confirmed as defense secretary, but officials caution that many of the other Senate confirmed positions may not be filled in the first 100 days of the new administration and will continue to be carried out by career civilians.

The other constant is the uniformed military leadership, which serves the commander-in-chief regardless of political affiliation.

Chairman of the Joint Chiefs General Joe Dunford and his Joint Chiefs of Staff watched as their new commander-in-chief was sworn in today, saluting President Obama as he walked into the ceremony, and President Trump as he departed.

ODNI and CIA

In Director of National Intelligence James Clapper’s farewell message to the Intelligence Community Thursday, he named Mike Dempsey, formerly the deputy director for Intelligence Integration, as the acting director until President Trump’s nominee, former Senator Dan Coats of Indiana, can be confirmed.

Coats’s hearing process before the Senate Committee on Intelligence hasn’t begun, and the other three appointments within the Office of the Director of National Intelligence have yet to be named, but Nick Rasmussen is expected to remain director of the National Counterterrorism Center until Trump names a nominee to that post.

At the Central Intelligence Agency, Director John Brennan effectively stepped down when President Trump swore the oath of office, leaving Meroe Park the acting director.

Republicans pushed for nominee and Kansas Rep. Mike Pompeo to be confirmed Friday, but Democrats led by Chuck Schumer have indicated that they need more time to debate before a vote is held.

“We look forward to beginning a debate on Congressman Pompeo in the hopes that he can also receive a quick vote,” Schumer said Friday afternoon.