Scottish Labour lost the May election because of infighting over control, a poorly thought out manifesto and the facts that the party had little momentum or a positive message.

That is the finding of a review of the campaign by one of those closest to the former first minister, in a hard-hitting internal memo that has been leaked to The Herald.

It concludes that Labour has failed to "pursue power for a purpose", that it lost its focus on winning, and that it is essential that focus and purpose are regained.

It also says MPs, MSPs and councillors failed to work together in the campaign, and they risk further losses, including Scottish seats at the next Westminster election, if candidates continue to "stand separately and swing separately".

The review was written by Adrian Colwell, who was one of nine Labour special advisers working closely with Jack McConnell during his time as First Minister from 2001 until this year.

It is the first candid assessment to be made public about a poorly organised Labour election machine. It also blows the lid off the silence within the party, ahead of the MSPs group meeting in Dunkeld on August 20 and 21.

Around that event, there is a growing expectation that Mr McConnell will announce he is standing down, with Paisley MSP Wendy Alexander the front-runner to replace him.

The Colwell memo says the leadership in future has to be more team-based and less "presidential", and there is a dig at his former boss's international profile, saying: "We need devolution delivery, not foreign policy fantasies."

The election assessment is dated May 18, less than two weeks after the result put the SNP one seat ahead of Labour, and Alex Salmond became First Minister.

It is circulating within Labour circles and is thought to be part of a review of the campaign being carried out by Lesley Quinn, Scottish Labour's general secretary.

The Colwell memo states the campaign was "relentlessly negative with little that can be judged to be positive.

"The national organisation was hampered by in-fighting over who was in control, while local organisation was patchy. It seemed that the party has been hollowed out," though in some places candidate effort and headquarters support made a difference.

He wrote there was no strategy to win regional list seats, even though they are becoming more important to Labour and were vital to the SNP's success. There is a recommendation to learn from the SNP's "single-minded, relatively positive" campaign, while questioning whether the focus on attacking the SNP built up its profile.

"Our economic attack was complex and did not appear to resonate, as it conflicted with the feeling people have with a strong, growing economy.

"In some respects, the campaign against us was strong on aspiration, feel-good, well-being and quality of life."

The memo goes on: "We focused almost exclusively on attack and did not present or defend our record. We did not suggest momentum; that Scotland was becoming a better place. In contrast, the SNP offered the hope for something better."

It is claimed the manifesto was "written by a cabal behind closed doors", having changed its focus from what had been agreed within the party and at the Oban conference last November, and presentation of it was "poor" compared with rivals.

"Where were the new ideas, the big ideas, the policy and narrative coherence necessary to present a coherent view of what a party aims to use power for?" Mr Colwell wrote.

"The overwhelming feeling one was left with was complacency, of taking people and places for granted."

The assessment goes on to argue there were major weaknesses in the manifesto; education was "not thought through", it failed to campaign on costly health promises, the message on justice was "weak", there was little new to say on transport, the economy and cities, the environment message was not coherent and the planned reforms for council tax "fell apart".

Among a range of recommendations, Mr Colwell said Labour MSPs have to be challenged to be an effective opposition, that they should contribute new ideas, "to think about these questions, not sit back waiting for tablets of stone to be presented".

"We need to start thinking about 2011 now and orientate our strategy for winning back power through a combination of new language and vision, new policy and thinking about how to improve delivery when in office."