Who is the most important person to President Bush's re-election hopes?
Political adviser Karl Rove? Defence Secretary Donald Rumsfeld? Vice-President Dick Cheney?
Many Americans now suspect the war may not have been necessary
All will undoubtedly play some role in how November's presidential election turns out, but arguably the man who will trump them all is Iraq's Prime Minister Ayad Allawi.
Following Monday's hurried transfer of power to the interim Iraqi government, Mr Allawi is now responsible for getting Iraq back on its feet and going after the insurgents and militants who have killed hundreds of Iraqis - and a good few Americans - this month alone.
And his success in stabilising his country will have a direct effect on Mr Bush's chances of getting another four years in the White House.
If Mr Allawi can devise and implement a programme that shows genuine progress in Iraq, then Mr Bush can forcefully claim that the costs of the conflict have been worthwhile
The failure to find weapons of mass destruction is moving the Iraq conflict, in the minds of many voters, from a war of necessity to a war of choice.
And along with that shift has been a steady decline in how Americans view the commander-in-chief who made the ultimate decision.
Mr Bush's approval rating is around 47% in most opinion polls, and the political brains within the Republican party will know as well as anyone that, historically, that is not encouraging.
Allawi is far away, but central to Bush's hopes of re-election in 2004
Since 1948, only one incumbent president who had an approval rating below 50% in June or July of an election year went on to win the subsequent ballot. And that was Harry Truman in 1948 itself.
All the others either lost - George H W Bush, Jimmy Carter, Gerald Ford - or didn't run - Lyndon Johnson and Harry Truman in 1952.
And not only is the situation in Iraq reducing the president's overall standing. It is diminishing Mr Bush's advantages over Democratic challenger John Kerry in his strongest attributes - combating the threat from international terrorism and being a strong leader.
So the decisions that Ayad Allawi makes over the next few weeks and months - backed up by nearly 140,000 American troops - are likely to have a direct effect on Mr Bush's chances.
If the prime minister is assassinated or cannot improve security for both Iraqis and Americans or is blamed by ordinary Iraqis for the everyday problems that are undoubtedly going to continue, then it will become very difficult for the president to win over the ever-growing number of Americans who think the war was a mistake.
But if Mr Allawi can devise and implement a programme that shows genuine progress in Iraq, then Mr Bush can forcefully claim that the costs of the conflict have been worthwhile, and that with Saddam Hussein safely locked up, the United States and the world is a safer, better place.
That's the campaign message Bush-Cheney 2004 long planned to deliver.
With the transfer of power now complete, it looks as though they have played their final hand and must now wait for Ayad Allawi to decide how he handles the cards he has been dealt.