American presidents are meant to have big ideas about the world: a "new frontier", an "alliance for progress", a "war on terror". Unfortunately for the Democratic party the big idea that most animates their two would-be presidents - Barack Obama and Hillary Clinton - seems to be mutually assured destruction.

That has left the field open to Senator John McCain. The Republican is currently the only presidential candidate to champion a striking new idea about America's role in the world. The world should pay attention, since the chances of Mr McCain winning the presidency are going up by the day.