A year ago, when jubilant Iraqis toppled the statue of Saddam Hussein after a lightening quick military campaign Mr Bush seemed a shoe in for a second term.
So, what has happened since then? Firstly, post conflict Iraq has proved much more difficult than the Americans expected. The recent turmoil might just have been a low point before power is handed over in June. But things could still get worse in Iraq before they get better.
Secondly, the Democrats have chosen a grown up as their presidential candidate.
The Democrats had been in turmoil since Bill Clinton left the White House. Internal wrangling between Clintonite modernizers and more traditional Democrats threatened to derail any campaign to unseat President Bush. But in rallying round John Kerry the Democrats were opting for the man they thought had the best chance of beating Mr Bush.
Senator Kerry still has a number of mountains to climb. He is from Massachusetts in the North East. The American population and political power have been shifting south over the decades. Both the last two successful Democrats � Clinton and Carter � were southerners.
It is also extremely rare and increasingly so for an established Washington politician like Kerry � a long serving senator � to win the presidency. Americans have tended to prefer state governors whom they see as untarnished by the wheeling and dealing they dislike in Washington.
The Republicans are examining Kerry�s voting record with a fine toothcomb. They are already bombarding the airwaves with attack ads highlighting those aspects of Kerry�s record they see as inconsistent or unpopular.
After two years� of a �jobless recovery�, growth in the American economy does now seem to be creating new jobs and a sizeable majority of US voters still support Mr Bush on Iraq.
So Mr Kerry has his work cut out, but the election is not the foregone conclusion it was.
