This role was almost constitutional. Half a century ago, Franz Josef Strauss, leader of the C.D.U.’s Bavarian sister party, the Christian Social Union, justified his own rock-ribbed conservatism by saying it came with a guarantee that “no legitimate political party” could exist to his party’s right. Many felt they could trust Mr. Strauss to police the country’s rightmost ideological boundary.
But in electoral politics, or game theory, or whatever you want to call it, there is a fallacy in such an arrangement. Ms. Merkel was not slow in discovering it: If there really were no legitimate viewpoints to the right of the C.D.U., then the party’s optimal strategy would be to move ever leftward, which it could do with no fear of an alternative right-wing party ever outflanking it.
And this is what Ms. Merkel did, whether out of idealism or calculation. In the wake of the Fukushima meltdown of 2011, she announced an exit from nuclear power, long sought by the Greens. In 2015, she joined Social Democrats in passing a minimum wage. In 2017, she secured a vote legalizing gay marriage (without voting for it herself). Most crucially, in 2015, she announced that Germany would welcome hundreds of thousands of migrants fleeing the war in Syria, creating a continentwide political crisis that, among other consequences, arguably drove Britain out of the European Union.
The effect on German politics was unnerving. The Alternative for Germany party, up to that point a wonkish group obsessed with the European Union’s monetary policy, changed its focus to immigration in July 2015. The following March — eight months before Donald Trump’s election — the party harvested 13, 15 and 24 percent of the vote in state elections. In 2017, Alternative for Germany, now well established on the C.D.U.’s right, not only sent nearly 100 members to the Bundestag; it also became the leading opposition party. It appeared that Ms. Merkel was heedlessly allowing votes to drain out of her party into an American-style populism.
Ms. Merkel, of course, is not the first conservative politician to poach voters from her progressive opponents. But certain problems come predictably with this strategy. The leader benefits more than the party’s rank and file, because the landscape of progressive issues is foreign territory to them. In last month’s rout, things that Christian Democrats might ordinarily have talked about and rallied kindred spirits around — Covid-19, migrants, the euro — were suddenly off limits. The rank and file fell silent. In last week’s elections, the C.D.U. lost half its voters from the previous ones. Fewer than 3 percent defected to Alternative for Germany. The lion’s share went to the Social Democrats, the Free Democrats and the Greens.