Labour has enjoyed a surge of support in the past week and is now just four points behind the Conservative Party, according to a poll released tonight.
The ICM survey for The Guardian suggests that the Tories have yet to establish a firm lead and that Labour could even emerge from the general election with the most MPs.
Whichever party came first, the findings indicate either of them would be forced to rely on Liberal Democrat support.
After a series of recent polls suggesting the Tories were pulling away again, tonight's shows there is still all to play for as Gordon Brown prepares to call the election tomorrow.
It puts Labour up four on 33 per cent since last week, and the Tories down one on 37 per cent. The Lib Dems are down two on 21 per cent.
The ratings are the best for Labour in an ICM poll since December 2008 and the Tories' worst since February.
The Guardian reported that, on a uniform swing, Labour would be left 30 seats short of a majority.
However, the Tories are expected to perform better in marginal seats they have been targeting their resources at.
A further poll issued tonight gave the Tories a commanding 10-point lead - generally seen as the kind of margin they need to win a Commons majority.
The Opinium survey for the Daily Express put the Tories on 39 per cent and Labour on 29 per cent, both up one point on last week.
The Lib Dems were on 17 per cent, down one.
Opinium Research interviewed 1,903 adults, representative of British adults, online between April 2 and 5.