For German Social Democracy, Europe is vital to the national interest.

CDU head Angela Merkel has tried for years to serve two sides: the conservative side by holding up her CDU party membership. But then at the same time she acts as though she were also a Social Democrat. I don't have this hydra-headed nature. In the end, people will vote for the Social Democratic original.

I spoke with Gerhard Schröder about a lot of things, including foreign policy. Schröder knows how important European policy is to me personally. I have worked together with Angela Merkel on European policy for many years, so I was surprised when Volker Kauder who has little experience in European policy, claimed that I had not represented German interests in Europe. That's an example of how the conservatives conduct an election campaign.

The quota idea is a good one, but there are two problems with it. The first is clear: A quota system would also require all European countries to be prepared to take refugees. And secondly: What happens when the quota has been filled? Would we then simply tell those who are threatened, sorry but we have to send you back?

Businesses will only invest in Greece if three conditions are fulfilled. First, there must be a clear commitment to the euro. No businesses will invest if they have to fear that Greece will leave the euro zone at some point. Second, the Greek government must be prepared to work together with European institutions in order to restructure the country.

You have to let the people vote when it comes to a new constitution.

[Recep Tayyip] Erdogan is an adherent of realpolitik. He knows that international relations are not built on the strength of unilateral demands, but on solutions that are in everybody's best interest.