In the late 1990s, she became involved in local politics in the Hanover region, and she served as a cabinet minister in the state government of Lower Saxony from 2003 to 2005. In 2005, she joined the federal cabinet, first as Minister of Family Affairs and Youth from 2005 to 2009, then as Minister of Labour and Social Affairs from 2009 to 2013, and finally as Minister of Defence from 2013 to 2019, the first woman to serve as German defence minister. When she left office she was the only minister to have served continuously in Angela Merkel's cabinet since Merkel became chancellor. She served as a deputy leader of the CDU from 2010 to 2019, and has previously been regarded as a leading contender to succeed Merkel as chancellor and as the favourite to become secretary-general of NATO.