BERLIN, Germany — Since Angela Merkel became German chancellor in 2005, few contenders have even come close to challenging her dominance, even in the wake of unpopular stances like her open-door policy toward refugees.But in a shifting global climate that has spawned political earthquakes such as Britain’s exit from the European Union and President Trump’s entry into the White House, even the so-called Iron Chancellor may not be as invulnerable as once believed.
