Lord Ashcroft's poll of 12,000 voters shows a tighter race than the surprising numbers in the national exit poll.
Ashcroft, speaking on London radio's LBC, said his poll had the Conservatives at 34% to Labour's 31%, suggesting a much tighter race than first thought. The Lib Dems had 9% of the vote and UKIP was on 14%.
The national exit poll had the Tories winning 316 seats to Labour on 239 seats, putting David Cameron just 10 seats off winning a majority.
"It's nowhere near what the exit poll suggests," said Lord Ashcroft, referring to the poll released at 10pm.
The Conservative peer also revealed 33% of those polled made up their mind on who to vote for last week and 11% decided on polling day.
It suggested that those who decided late, slightly went for Labour.
Of those who decided in the last week, 27% went to the Tories and 30% to Labour.
And there were breakdowns of which leaders people preferred.
UKIP voters preferred Cameron to Miliband by 56% to 13%
Labour voters preferred EM over DC by 79% to 7%, but 13% said they didn’t know
Lib Dem voters preferred Cameron to Miliband by 52% to 21%