Yet she will probably face the toughest election of her career; victory is far from assured.

The German parliamentary democracy doesn't impose term limits on chancellors. Yet voter fatigue with a leader who will have run the country for 12 years by election day will be a factor. "You know me," Merkel told voters in 2013; and they liked what they knew. Now, Germans may know Merkel a little too well for comfort. And many suspect that, for all her skill at working out impossible compromises and pulling out of impossible situations, she doesn't really have a plan for taking the country forward, whether tackling refugee integration or social security reform.

In addition to a speech declaring her candidacy, Merkel gave an interview to TV anchor Anne Will, explaining that her goal was to promote "cohesion" in society with her measured, centrist approach. She argued Germany would need her experience at a difficult time.