As the Democratic candidates survey the primary calendar ahead of them, each of them will be making careful calculations about who is most likely to support them, where those supporters are and how to get them to the ballot box.
If there is one thing that the 2000 election between Al Gore and George W Bush showed, it was that every vote could count.
Howard Dean is a hit with younger Iowan voters
Iowa goes first with its caucus and turnout is everything here.
Persuading people to spend hours debating and voting for a candidate requires greater organisation on the part of campaigns and greater commitment on the part of caucus goers than simply putting a tick in a box at a primary in New Hampshire.
This means Iowa will be a good indication for the organisational power of the campaigns and their ability to get their key target groups to make good their promises of support.
Currently four candidates are close to each other in Iowa - Howard Dean, John Kerry, Dick Gephardt and John Edwards.
Any of them could win.
For Dick Gephardt, Iowa is "do or die" as it is where his supporters are most prevalent.
Mr Gephardt won here in 1988 and comes from another mid-western state.
His agenda - which stresses jobs, trade, and economic issues - matches that of Iowans more than New Hampshire or most of the other early primary states, and he will be hoping that his allies in the manufacturing unions will bring out the votes for him.
Dick Gephardt is no stranger to victory in Iowa
Howard Dean's campaign has been driven in large part by younger voters and their enthusiasm will be harnessed by the Dean campaign in Iowa.
Something like 3,500 young people are coming to Iowa although other campaigns have claimed that Dean may be bussing in volunteers from out of state to take part.
Iowa will show whether the "deaniacs" really can make a difference on the ground.
Mr Dean also does best amongst more affluent voters and liberals who tend to be more bothered about Iraq - the type of people who, fortunately for him, are significant in New Hampshire which holds the first primary on 27 January.
Senator Kerry is hoping for former and current 'soldier support'
That is one reason why Mr Dean has a more commanding lead here as opposed to more domestically-focused Iowa.
But he will be worried by recent signs that some of those who initially supported him are now having second thoughts.
Victory looks likely for Mr Dean in New Hampshire but the margin is critical.
John Kerry meanwhile will be hoping that sizable veterans populations in Iowa and also South Carolina might be his secret weapon (although as a retired General, Wes Clark may be hoping the same thing).
Mr Kerry has mailed out 26,000 videos to supporters in Iowa and has been emphasising heavily his time in Vietnam in the hope that veteran's votes in these two states might save his campaign if it loses New Hampshire.
For John Edwards, South Carolina on 3 February will be the critical test.
All election hopefuls will be courting the state's all-important 'black' vote
He has built much of his campaign message on the basis that only Democratic presidential candidates from the South can win the general election (the last non-Southern Democrat to win was John F Kennedy 44 years ago).
Mr Edwards also comes from the neighbouring state of North Carolina.
As with Mr Gephardt in Iowa, there will be a sense that if Mr Edwards cannot win in South Carolina he probably cannot win anywhere.
South Carolina is also important because of the black vote (which is a quarter of the state and likely to be about half the turnout of the Democratic primary).
Questions have been raised about Howard Dean's ability to reach out beyond middle class white liberals (who are dominant in New Hampshire) and South Carolina may provide the answer.
Mr Clark is not competing in the Iowa caucuses but is in New Hampshire
Meanwhile, Joe Lieberman will be hoping to kick start his disappointing campaign in Arizona.
He has worked hard to try and win over the Hispanic vote which makes up a quarter of this state.
No candidate has yet demonstrated an ability to draw in voters from across the nation and across the spectrum of the Democratic party - but all that may change as the voting begins.