Von der Leyen declared that the EPP would build a "bastion" against extremes from left and right.
"As of tomorrow, we have to work for Europe, for the European citizens, and we will deliver," concluded von der Leyen.
EPP President Manfred Weber said concerns over the rise of anti-European parties "who want to destroy Europe" did not materialise.
"That was the concern, that was the fear," said Weber. "We don't see the figures now, dear friends, that I'm proud," he stressed.
"People know that the left is not delivering on their concerns. We are delivering on migration, we are delivering on economic laws we are delivering, also keeping peace in Europe," said Weber.