Countdown:
42-33: the worst ten presidents
32-22: the let-downs
21-11: the nearly-greats
10-1: the greatest presidents

And so we begin. With the world's most important general election now only a week away, and the potential for a result with seismic political ramifications, The Times presents the biggest presidential debate of them all. Namely: who's the greatest?

Eight of our top international and political commentators sucked the ink from their pens as they anguished over the task at hand - to rank, in reverse order, all 42* presidents of the United States.

We asked our panel to rank the presidents in order of greatness. The Collins English Dictionary definition of great reads thus: relatively large in size or extent; relatively large in number; having many parts or members; of relatively long duration; of larger size or more importance than others of its kind; extreme or more than usual; of significant importance of consequence; of exceptional talents or achievements; remarkable; doing or exemplifying something on a large scale; arising from or possessing idealism in thought, action etc; heroic; illustrious or eminent; impressive or striking; active or enthusiastic; skilful or adroit; excellent, fantastic.

Phew . . . that's a tall order to meet, even if you win two terms in office. So when our experts came to consider the merits of the 42 men to have held office, they had to look at a multitude of achievements - some of them short-term, others which have changed the course of history.

Gerard Baker, US Editor, writes: "Trying to rank 42 of anything is difficult. Imagine if someone gave you 42 universally acclaimed music albums and then asked you to put them in order of quality.

"It’s especially tricky because, I would argue, like most people, the 42 American presidents fall into a well-established, Bell-curve or normal distribution on a chart – a handful of outstanding ones, a handful of duds, and a lot of so-sos.

How America's presidents rated

The Times has ranked all 42 US presidents - was Bush Jr. bottom? Did JFK beat Abraham Lincoln?

Multimedia

• Across the pond: blogging the election

• Full coverage and analysis of race for White House

• Podcast: satrical view from both sides of the Atlantic

Related Links

• The 10 worst presidents to have held office - The Times US presidential rankings

• The Times US presidential rankings

• Who's the greatest? The Times US presidential rankings

"I couldn’t, in all honesty therefore, really say that number 13 on the list is that much better than number 30."

Tom Baldwin, our Washington Bureau chief, agrees: "This is subjective and clouded by our own historical perspective. I found it hard to place high up on the list slave owners and those who sanctoned the slaughter of Native Americans. Nor do I much like those who reduced America to civil war or appeased the South afterwards.

"Reagan gets lower marks than others might give him because his economic philosophy can be blamed for much of the world's troubles now. Clinton is higher than he might have been because he cleared federal deficits, partly through Congressional stalemate. Lyndon Johnson deserves more credit for civil rights than Kennedy."

Richard Beeston, The Times Foreign Editor, writes: "America has already selected many of its most impressive leaders as Mount Rushmore, the Washington monuments and the faces staring out of dollar bills reveal. The easiest part is choosing the top 10. The hardest is weighing up the qualities of men like John F Kennedy - glamorous, eloquent and popular but who was assassinated before he had the chance for history to judge his legacy fairly - against leaders from another age in America’s short but frenetic history."

As if to prove how huge a task this was, Daniel Finkelstein, the Times chief leader writer, pooled resources with his colleague Oliver Kamm while deliberating "to ensure that we knew enough about all the Presidents to deliver a judgment on each".

But did they get it right? Or is there even a right answer? Have your say as we count down the rankings today and for the rest of the week, beginning today with the bottom ten - numbers 42 to 33 - and continuing tomorrow, Thursday and Friday.

* One for the anoraks: Grover Cleveland is both the 22nd and 24th president, having won a return to office four years after losing the seal.

The panel

Chris Ayres, Los Angeles correspondent

Gerard Baker, US Editor

Tom Baldwin, Washington Bureau chief

Richard Beeston, foreign editor

Camilla Cavendish, columnist

Daniel Finkelstein, chief leader writer

Ben Macintyre, writer at large

Bronwen Maddox, chief foreign commentator

Times Recommends

• African migrants desperate for a better life
• Karzai, the Anglophile who alienated the West
• They killed my family, but I rise again