FEW GERMAN politicians divide opinion like Sahra Wagenknecht. A Putin-loving demagogue to her detractors, simply “Sahra” to her legions of adoring fans, Ms Wagenknecht has injected a high-octane blast of populism into a country that prefers its politics staid and consensual. Invariably decked out in her trademark high-necked jackets, Ms Wagenknecht rules the airwaves with her brainy but pointed polemics on Ukraine, immigration and other prickly subjects. Her political formula is unorthodox, yet the success of her Sahra Wagenknecht Alliance (BSW), a party she launched only in January, proves a talent for political entrepreneurship. And she has developed an uncanny knack for forcing other politicians to dance to her tune.