Succession campaigns take place when the incumbent government party enters a race with a new top candidate. In the U.S., successful examples are rather rare at the national level. Only George H. W. Bush in 1988 was able to win a third term for his party, following two terms of Ronald Reagan. Hillary Clinton failed to achieve the same thing for Democrats in 2016, when she tried to succeed to Barack Obama after his two terms at the White House.
In Germany, Armin Laschet is currently trying to succeed to Angela Merkel. To ask voters for four more years after sixteen years in power is quite a challenge. I always say that a good election campaign is a series of strategic decisions. It seems to me that Armin Laschet has (still) not answered the most fundamental question: does he own the sixteen Merkel years or is he trying to distance himself?
An extreme version of the distancing strategy was Nicolas Sarkozy from France. If you think about it, he was the president of the incumbent governing party, and served twice as minister in the government of the incumbent president Jacques Chirac. But Chirac and Sarkozy were so much at odds with each other that Sarkozy was able to successfully run as a “change” candidate.
I have done several succession campaigns for mayors and governors myself. In most cases, the successor has to strike the right balance between taking credit for the good things that happened during the incumbent government, but also portraying himself as his own man. In other words, the job approval rating of the incumbent is the wind in the back of the successor, but it can not be the main message itself. It is also important to note that it takes a lot of time to establish the successor as his own man. It is therefore crucial for succession campaigns to be planned in a long-term perspective. This is why wannabe successors that come out of nowhere shortly before an election often fail.