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.
And there were breakdowns of which leaders people preferred.
Mark Di Stefano is a media and politics correspondent for BuzzFeed News and is based in London.
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