Barack Obama: “Well, let's be clear about who John McCain's fighting for. He's not fighting for Joe the Plumber. He's fighting for Joe…”

It is a basic principle of American democracy that the government can’t selectively target individuals simply because of their political beliefs or what they say.

The fact that any president, or any administration, is willing to engage in such transparent efforts to intimidate someone should outrage all Americans, regardless of how they feel about Congresswoman Omar’s political views.

When we choose, when we make that decision, I do believe – and there is evidence for this – that the world gets incrementally better, and that is a worthy goal and it’s worth fighting for.

If I had a blame pie for why politics is so polarised and why we're seeing a rise of populism in many places, it's because of that information that is going into our brains every day.