In political life, it is extremely difficult to remain loyal to a friendship when constellations of power or interests are in the way.

We have committed ourselves to pursue joint policies, but then national governments say, "We aren't bound by that." That is a dramatic situation, because solidarity is a basic principle that cannot be had on an à la carte basis. If we have rules that nobody adheres to, then the community will break apart.

The Social Democrats have to listen to people who are attracted to the AfD party. That isn't a mistake at all. You can also win them back. Of course, there are a lot of angry voters who are ideologically charged. But there are also a lot of quieter voters who plan on voting AfD to send a message. We can never give up on them.

The vast majority of people support the idea of an enlightened, modern union of countries demonstrating solidarity. Film director Wim Wenders recently summed up the problem to me very well. He said the idea of Europe has become an administration, and now people think that the administration is the idea. But that doesn't mean we should give up on the idea - it means we should change the administration.

My worry is that Donald Trump may inspire copycats, also in Europe. That's why I hope Hillary Clinton wins.

Many who have voted for the AfD, or who intend to do so, aren't doing so because they are dyed-in-the-wool enemies of democracy. Rather, they are desperate.

If you say in advance there is going to be a main candidate and then that doesn't count later, then that's going to be a highly problematic occurrence in a democracy.