Mr Rau was prised out of his throne in North Rhine-Westphalia, the most populous Land in Germany, with more than a little help from Gerhard Schroder, the SPD's chancellor candidate. After 19 years as regional prime minister, reigning over 17 million people, he is to be succeeded by Wolfgang Clement, a close Schroder ally.
At first glance, the swap is a brilliant marketing ploy. Mr Rau quits at the age of 67, in the year when 67-year-old Helmut Kohl is going for his fifth term as Chancellor. With a growing majority of Germans exasperated by Mr Kohl's political longevity, setting an age of retirement for politicians can only help the opposition's cause.
The Social Democrats will now follow into battle a - relatively - spritely Mr Schroder, aged 53, flanked by Mr Clement, a mere 58. On the German scene, where advancement is strictly in accordance with the "dead man's shoes" principle, the tandem counts for a generational change.
The new packaging, which has already sent the SPD's poll rating to dizzy heights, conceals substance that the Schroder campaign has so far lacked. The chancellor candidate is a practitioner of right-wing economics; to the delight of business but to the dismay of his own party.
Mr Clement is on the same wavelength as Mr Schroder, but has until now been unable to enter debate about the kind of policies that a new Social Democrat government should pursue. Disagreements between Mr Schroder and the rest of the party have paralysed efforts to forge a programme.
The unveiling of the manifesto scheduled for earlier this week had to be postponed because the party presidium could not agree on details of their "most market-oriented" programme to date. It made all the right noises about investment and the need to modernise, but fell short of the specifics business hoped to see.
The next attempt will come at the SPD's national conference next month. Unlike previous occasions of its kind, Mr Schroder will no longer stand on the rostrum completely alone. The regional party that is now under Mr Clement's thumb accounts for one-third of conference delegates.
Besides trying to impose their will on their own party, the two men are also challenging assumptions about the SPD's future coalition partners. Mr Clement inherits a fractious Red-Green government in North Rhine-Westphalia, beset by acrimonious rows over the environment.
The Greens are aware that their cause will find even less sympathy with the new prime minister, just as the environmentalists in Bonn can expect few favours from a future Chancellor Schroder. The latter has already served notice that unless the Green leadership can whip their fundamentalist troops into line, they can forget a place in the new government.Reuse content