It is impossible to swear an oath to the German Basic Law without realizing that our constitution is among the most liberal constitutions in the world. As the head of government in such a country, I would stand up to all those who call into question this free, open and tolerant model of society.

We need to roll back precarious employment models. Temporary and limited contracts were initially seen as a way of introducing more flexibility so as to bridge periods of need in certain phases of production. Some employers have taken advantage of the model to push down wages. In general, we must strive for equal pay for equal work.

Britain, Europe's second largest economy, a member of the G-7 and the UN Security Council, wants to leave the EU. That weakens us and it weakens Britain.

Solidarity is the fundamental idea of European cooperation. If a country feels itself to be militarily threatened and calls for soldiers, weapons and sanctions, then that's what it gets. When governments say they need money from the structural funds to stabilize their economy, that's what they get. But you can't cherry pick solidarity.

The construction of social housing and the attempt to support families seeking to buy their own homes are all projects from the 1960s and '70s. It all sounds old-fashioned, but it is actually completely modern.

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.

Donald Trump is betraying everything that made America great: tolerance, democratic institutions and respect for the individual. In that sense, Trump is the most un-American U.S. president that the country has had in a long time.