· A message out of step with an electorate that desperately wanted change.

· Failure to devise a plan B...

· Failure to build a grassroots organization. The campaign, caught up in its self-created myth of invincibility, also lost track of spending, burning through $120m (£61m) so fast that Clinton could not run television ads in several key states in February.

· Mishandling the campaign's greatest asset - Bill Clinton - turning him into one of his wife's greatest liabilities.

The first signs that Obama could pose a serious threat to Clinton's ambitions emerged last summer. Field organisers in Iowa reported back to headquarters in Arlington, Virginia, that voters were cool to her emphasis on experience. Iowans wanted change, and anything associated with Washington was viewed as tainted. That was a rebuff to the central premise of Clinton's campaign, derived by her then chief strategist, Mark Penn, that in the post-George Bush, post-9/11 world voters would feel safer with a more experienced candidate. Penn left the campaign in April amid controversy over his work for outside clients, especially the Colombian government.