In a dramatic demonstration of their drift to the right since September's elections, the Christian Democrats are taking their crusade into the streets. With their Bavarian allies, they intend to collect millions of signatures in defence of the 1913 citizenship law, which provides a racial definition of what it is to be German.
A new law, a compromise thrashed out by the Social Democrats and Greens, would grant automatic German citizenship to third-generation immigrants born in Germany, and ease the naturalisation process for other long-term residents. Of the 7.2 million "foreigners" living in Germany, about 4.2 million would qualify.
As matters have stood since the days of the Kaiser, German citizenship has been legally defined as a genetic attribute. The descendants of Germans settled in Russia in the time of Catherine the Great are Germans, and can "return" to Germany. Grandchildren of "guest-workers" who arrived in the 1960s remain "guests", and face bureaucratic hurdles every time they renew their temporary residence permits.
Naturalisation is slow and cumbersome. The recipients must surrender their original passport and citizenship. In the case of Turks, who number more than two million, they must buy themselves out of Turkey.
Under the law, which is due to be enacted by the summer, the newcomers would be allowed to have dual nationality for the first time. This, the opposition believes, will provoke "envy and aggression" among the natives.
"The consequences could be horrific," said Wolfgang Schauble, Helmut Kohl's successor as CDU chairman. A hard-hitting policy paper drawn up by its Bavarian sister party goes even further. "Germany's inner peace and integration are in danger," the Christian Social Union declares. The new law would provide a "hot-bed for racist incitement".
The government, and even the Free Democrats who used to be in Mr Kohl's coalition, counter that the petition is whipping up passions of the wrong kind. "It's all about mobilising prejudices," said Ottmar Schreiner, party manager of the Social Democrats.
Edmund Stoiber, the Bavarian Prime Minister, likened the foreign peril to the "threat posed to national security by the Red Army Faction", the urban terrorist group in the 1970s and 1980s. Mr Stoiber fears the new Germans will breed and attract "hundreds of thousands" of relatives from their previous homelands. "The German people don't want that," he said. "The people feel that the limits of our identity as Germans are bursting open."
Mr Stoiber's government in Munich has done much to protect German identity in the past. Last autumn, it "sent home" a 14-year-old thug to Turkey, even though the boy had been born and brought up in Germany by his Turkish parents. Bavaria has also lobbied strongly on behalf of nationalistic exile groups of Germans driven out of Eastern Europe after the Second World War.
The CSU policy paper, due to be published tomorrow, proposes to clamp down on immigrants even further. New arrivals would face language tests. Children aged 10 or over not conversant in German would not be admitted. Applicants would also face a test of knowledge of Germany's parliamentary democracy.Reuse content