A leading Tory donor has attacked Lord Saatchi for publicly criticising the party's general election campaign.
The Tories have been landed with a bill for the posters
Lord Saatchi published a pamphlet after quitting as party co-chairman criticising his own campaign strategy.
But businessman Tom Cowie said the party needed such criticism "like a hole in the head".
His words follow a row over the amount paid by the Tories to Saatchi advertising companies.
Mr Cowie said it was "extremely disconcerting" to see the figure of £1.5m quoted in an article in The Times newspaper as the bill from Saatchi companies for general election advertising work.
But that figure was disputed by Immediate Sales, part of the M&C Saatchi group, which said its fees were only £769,000 - and that Immediate had been the only Saatchi company working on the election campaign.
Michael Moszynski, chief executive of Immediate Sales, said he did know how the Times had arrived at its figures, and would be making a formal complaint to the newspaper.
He said the company based the contract on the amount the government paid its advertising agencies.
Mr Cowie, who donated £500,000 to the Conservatives ahead of the election, said he was not happy with paying for what ultimately turned out to be a failed advertising campaign.
He told BBC Radio 4's The World at One: "I would have thought, as a businessman, you only pay if you get success and not if you get failure."
But he reserved most ire for Lord Saatchi's public criticisms of the election strategy he, Saatchi, had helped to devise.
"I think criticism of this nature should be made to the people concerned, not to be publicly published in all of the newspapers. I think that is really working against the course."
He added: "As a party we need this criticism like a whole in the head."
Lord Saatchi, who wrote in his pamphlet the party had fought a "Basil Fawlty election - don't mention the economy" - was not available for comment.
The row comes as senior figures in the party meet to decide what leadership election options should be put to a ballot of party members, at the end of September.
Conservative MPs are suggesting that the system of selecting a leader is changed, so that they have the final say.
Currently the MPs select two candidates and ordinary party members vote on them.
Former shadow education secretary, Damian Green, told BBC Radio 4's The World at One, he thought it was time for a change.
He said: "I think it's not just MPs who think that MPs should have the final say, most of the members of the party I've spoken to agree that in the end the MPs know best the people who they work with on a day to day basis - and so are the best people to take the final decision.
"The system that's been set up would involve a consultation of all the members, so they would express a view -- but in the end the decision should be taken by MPs because they just have the knowledge to take it."
Mr Green's view was backed by one of the party's biggest donors, spread-betting tycoon Stuart Wheeler.