Tory deputy chairman Lord Ashcroft insisted today that the televised leaders' debates had turned everything "topsy-turvy" for the Tories in the election.
The billionaire Tory donor said it appeared the Conservatives would "land" more than 300 seats.
But he added: "Whether it reaches the magical 320-plus, we have to sit and wait further."
Interviewed by BBC News, Lord Ashcroft said he "very much doubted" that controversy over his "non-dom" tax status had affected the Tories' showing in the election.
And he indicated that he hoped to sit in the Lords for "many years to come" under new rules which require peers to be domiciled in the UK for tax purposes.
With the Tories still looking short of achieving an overall majority, Lord Ashcroft identified the leaders' debates, which led to a surge in Lib Dem support, as a turning point in the election campaign.
"I think from the time the Conservatives were ahead we then had the debates, which has quite obviously turned everything topsy-turvy and what were natural assumptions before those debates changed the whole of the playing field.
"This is the type of result we are now seeing as a consequence of those debates."
Lord Ashcroft said it was a "balanced argument" whether the Tory leader should have taken part.
The debates had brought greater awareness of politics and increased turnout.
But he added: "If you took a pure strategic hindsight view, then you'd say you'd much prefer the Conservatives going into today 10 points ahead than three or four points ahead."
Lord Ashcroft said by pumping funds into key marginals, the Tories had achieved some "significant swings" but conceded it was a "mixed bag" across the board.
Lord Ashcroft said it was "a little academic" to debate whether the row over his tax status had damaged the party and the issue was now "irrelevant" because of the rule change.
If peers wished to remain in the Lords, they were deemed to pay tax on their "worldwide income".
He said: "I look forward to sitting in the Lords for many years to come."
Challenged again on whether the issue had damaged the party, he said: "I think anything negative for anyone in a party for a small period of time causes something adverse.
"As to whether it has affected this election, I very much doubt it."
He said there was no undertaking to be "fully taxed in the UK" in the correspondence at the centre of the controversy, which allowed him to take his seat in the Lords.
Asked if he wanted a job in a possible Tory government, Lord Ashcroft said: "I've already said I'm stepping down from the party and would like to now get back to develop my own commercial interests."Reuse content