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.

I had a bird’s eye view because the Treasury secretary, Nicholas Brady, was a close friend of Bush who was appointed to his position by Reagan in 1988. It was widely assumed that he had been appointed at Bush’s behest. In any case, Brady was asked to stay on by Bush and remained secretary of the Treasury for the next four years.

As a consequence, Treasury was spared the transition that occurred in every other department. Typically, when there is a change in party the incoming administration has task forces of experts who go into the departments to meet with senior officials and career staff to get a head’s up on what is going on, find out how the place operates on a day-to-day basis, who does what, what issues are in the pipeline and so on. It is common for those serving on transition teams to scout out jobs for themselves in the process.

Bush seldom had people ready to go to fill the vacancies he created by kicking the Reagan people out all at once on the first day of his administration—there were 3,000 to 4,000 slots to fill. It made it harder to hit the ground running and get traction on his own agenda. Another problem is that many of the people Bush wanted took a long time to get their nominations sent to the Senate and get confirmed. Although cabinet secretaries were confirmed quickly, many sub-cabinet officials waited months for confirmation, during which time career bureaucrats ran the show. Also, it was my observation that many positions remained vacant for far longer, with no evidence that anyone was poised to fill them.

And the outgoing Reagan people who were being forced out had no incentive to do any favors for their replacements, like advising them about who among the career staff were worth paying attention to and which should be avoided. Having an inexperienced new appointee made it easier for the career staff to pursue their own agenda, sometimes at the expense of the president.

Another problem is that many of the Bush appointees weren’t very good. Their principal claim to a job often seemed to have been some personal connection to Bush, perhaps dating back to his 1980 run for the GOP nomination against Reagan. Their technical qualifications for the job were sometimes tenuous. I remember looking into one of the Bush people who came to Treasury. As far as I could tell, her only qualification for the job was that her mother had gone to college with Barbara Bush.

As it turned out, almost all of the political appointees at Treasury moved on within a few months after the Bush administration took office and their positions were filled with Bush appointees. I was one of the few who stayed. I always suspected that every once in a while the Bush people needed to know what the Reagan people were thinking and that was my job.

I have no doubt that the same thing would have happened throughout the government had Bush simply kept on all of the Reagan people. He could have let it be known that it would be appreciated if they moved on sooner rather than later or as soon as their replacement was confirmed. In the meantime, he would have had people in place who were eager to please their new bosses in hopes of staying on or moving up.

I think some missteps might have been avoided by having deeper institutional memory among the political appointees. I know from experience that many of the new appointees wasted time reinventing the wheel and getting up to speed on the issues within their jurisdictions. And many weren’t eager to do much anyway—they were there to get a line on their resume and that’s about it. I remember one guy who waited a long time to get confirmed by the Senate and left very shortly after he finally got it. He became a prominent Republican lobbyist.

In the longer run, I think Bush paid a political price as well for canning almost all the Reagan appointees. They tended to be leaders of the GOP and the conservative movement in their states and communities, and held ill-will towards Bush that came back to haunt him in 1992. Bush lacked that reservoir of goodwill in his own party that Reagan and even Richard Nixon had when times got tough. Many former Reagan officials sat on their hands in 1992 or actively opposed Bush by supporting Ross Perot. None that I knew shed any tears when Bush was defeated.

So my advice to Mrs. Clinton is don’t repeat Bush’s mistake. Treat Barack Obama’s political appointees as allies, not enemies. Replace the people who have to be replaced quickly, such as cabinet secretaries and White House staffers, but consider keeping on the rest, for a while at least. As noted, people tend to move on soon enough—the typical political appointee only lasts about two years anyway.

Particularly in the case of officials requiring Senate confirmation, replacements should be carefully considered given the increasing difficulty of getting anyone though the various obstacles to a final vote. Mrs. Clinton might think about putting her people into positions that don’t require confirmation to provide guidance where necessary. Sometimes that’s all that’s needed to accomplish a policy objective; power doesn’t necessarily flow from a title. The secretary can take advice from whomever he or she chooses.

The transition is hard and short enough even when party control is not involved. It’s best to use the limited time available to establish policies that require immediate action soon after the Inauguration. Depending on what happens in the congressional elections, Mrs. Clinton may have a very narrow window of opportunity to achieve legislative action on her agenda and get confirmations not only for key staff but fill the backlog of federal judges and a Supreme Court justice as well. These actions will be helped by having experienced staff already in place on January 20.

In any event, I would strongly urge Mrs. Clinton to reject Bush’s policy of wholesale dismissals. She should remember that all of those people are loyal Democrats.