German Chancellor Angela Merkel expressed shock at the events such as Brexit referendum and the French presidential election.
She said she now believes it is worth fighting for a stronger Europe when addressing a campaign rally in the northern city of Zingst.
Germany will hold parliamentary elections in September. Merkel seeks a fourth term. Her prospects for re-election were bolstered by her party's victory in regional elections in May in North Rhine-Westphalia state.
She acknowledged the EU is not perfect, stressing it's more conducive to the prosperity and stability of the continent and the world if the EU states remain as a bloc.