With polling day fast approaching the parties are targeting all their firepower on the key marginals.
These are the constituencies that could change hands on Thursday - deciding which party will form the next government.
Labour is targeting its efforts on its "defence" list - the constituencies it won by a narrow margin in 2001 and which it will need to hang on to to preserve its Commons majority.
Most of these are constituencies where the Conservatives came second in 2001, mostly in the English Midlands, or where they are in a three or four way fight with Welsh or Scottish nationalists and the Liberal Democrats.
Tory 'winning post'
The party's private polling suggests some of its supporters could stay at home or vote Liberal Democrat - hence Tony Blair's warnings about "letting the Conservatives in through the back door".
Labour's two most marginal seats are Dumfries and Galloway and Dorset South, where it has a majority of just 0.3% over the Conservatives.
The Conservatives are fighting their campaign on two fronts.
Nine of their top 20 target seats are Liberal Democrat held. Their top target is Cheadle, where the Lib Dems have a majority of just 33, or 0.1%.
But despite going head-to-head with the Lib Dems in so many winnable seats, it is Labour supporters that must be the Conservatives' main target.
Of the 159 seats the Conservatives have to win in order to form the next government - assuming a uniform national swing - 122 are Labour held, with the English Midlands forming the key battleground.
The Conservatives' "winning post" seat - number 159 on its target list - is Halesowen & Rowley Regis, in the West Midlands, where Labour has a majority of 7,359, or 18.7%.
Lib Dem fight
The Liberal Democrats are in a straight fight with the Conservatives in many parts of the country.
Twelve of the Liberal Democrats' top 20 target seats are Conservative held - the other eight are Labour held Cardiff Central, Inverness, Nairn, Badenoch and Strathspey, Oldham East & Saddleworth, Dunbartonshire East, Bristol West and Birmingham Yardley.
But although the Lib Dems are enjoying their highest national opinion poll ratings since they were formed, they need bigger percentage swings in their target seats than the Conservatives.
For example, the Conservatives need a swing of just 3.8% from the Liberal Democrats to take Ludlow - number 22 on their target list.
The Liberal Democrats' 22nd most winnable seat is Bournemouth East, where they need a swing of 9.6% from the Conservatives to be in with a chance.
But - as they have proved in recent by-elections - the Liberal Democrats are skilled at targeting individual seats and they have several high profile Conservative scalps in their sights.
These include shadow chancellor Oliver Letwin in Dorset West, number six on their target list, with a majority of 2.9% and shadow home secretary David Davies, in Haltemprice & Howden, at number seven. with a majority of 4.3%.
All three parties agree that with so many regional variations and local battles going on, the national opinion polls can only tell part of the story.
And whatever the overall outcome on Thursday night, the contest seems certain to spring more than a few surprises.