Thursday’s Democratic gathering in Las Vegas, Nevada, is attracting much more attention than previous presidential debates, given the growing perception that Hillary Clinton is no longer cruising to victory. But there is little in the national and local poll numbers to justify such a large swing of conventional wisdom against Mrs Clinton’s prospects.

A month ago, Mrs Clinton had been all but crowned the Democratic 2008 nominee by the media. Today she is portrayed as acutely vulnerable, particularly to Barack Obama, who has increasingly called into question the former first lady’s “character and judgment”.