If Hillary Clinton wins, it will only be the second time since 1928 that a new president has succeeded one of their own party absent a death or resignation. The only other time this has occurred in the last 88 years was the transition from Ronald Reagan to George H.W. Bush. I worked for Reagan in the White House and transferred over to the Treasury Department late in his administration, where I stayed for the entire Bush administration, and saw that transition from the inside.
The transition is the most critical period in any new administration, often setting the course for everything that follows. The issue of personnel may be the most important.
Death and resignation are special circumstances where the new president is pretty much forced to keep on almost all of the previous president’s staff for the time being. Of course, eventually they end up with their own people, especially when they are elected in their own right, as was the case with Lyndon Johnson in 1964 and Harry Truman in 1948.
Bush made a fateful decision during his transition that I think hurt him badly both in the short run and the longer run—he decided to fire virtually all of the Reagan appointees as if the transition was from one party to the other. Obviously, when party control changes, all the political appointees of the previous administration know they will be expected to resign. But the Reagan appointees, all of whom supported Bush, who had been Reagan’s vice president for 8 years, expected better from a president of their own party. By cleaning house, Bush made it much easier for his transition people to get the jobs they coveted, but Bush paid a heavy price for this ill-advised policy.