Fascinating article by the excellent Larry Sabato on politico.com - although 40% or so of American voters define themselves as independents, only about 10% of them actually are. The rest lean clearly to one or other of the big parties, but are shy about it. Despite the rise in self-declared independents, American politics has become plainly more polarised, and he goes on to argue this implies a very tight re-election race for Barack Obama.