Scotland needs to have a national returning officer and one layer of government controlling elections, according to a hard-hitting review of the fiasco that hit the May 3 ballots this year. It is understood that Ron Gould, the Canadian elections expert who has led a five-month review of what went wrong at the Holyrood and council votes, will report this morning that the fractured nature of elections in Scotland needs to be confronted.

Instead of 32 returning officers, each having autonomy over their own count, he is thought to conclude that there should be a streamlined, national system with one person overseeing the process.

The report is understood to be critical of the division between the Scotland Office in Whitehall having responsibility for Holyrood elections, while the Scottish Government in Edinburgh oversees council elections.

Moving to a single tier taking control would be likely to mean a significant devolution of power from Westminster to Holyrood.

It could open the door to a change of voting system for the Scottish Parliament, as there is probably a majority in favour of moving to the electoral system used for the first time for local authorities this year, meaning preferential votes for multi-member constituencies. The Gould report is also thought to confront the controversial question of how parties can describe themselves on the ballot form, after the SNP used "Alex Salmond for First Minister" to gain a prominent position on the form.

The design of that ballot paper was the source of the main problems at last May's elections, when more than 150,000 votes were deemed to be spoiled because they had not been properly filled in. In several constituencies, that meant more spoiled ballots than the size of the majority.

This has been linked to the design of the ballot form being unclear, and there is likely to be criticism in the Gould report of the Scotland Office and Electoral Commission for their testing of the papers before they were used.

Ron Gould had a legal dispensation to examine the spoiled ballot forms, and his report will have the first assessment of what really happened when voters went into the polling booths.

The elections were also marred by the delay in sending out postal ballots, meaning some people were unable to vote. And with electronic counting machines being used for the first time in Scottish elections, there were serious delays when some scanners failed to work properly.

The blame is expected to be shared around the Scotland Office, for its decision on the new, single ballot forms; the Electoral Commission for its advice on the voting forms; the former Scottish Executive for defying widespread advice that it should not hold the Holyrood and council elections on the same day; on returning officers for poor co-ordination; and on the company that ran the electronic counting systems.

The report does not name anyone, which will be a relief, in particular, for Douglas Alexander, the International Development Secretary who was at the Scotland Office when key decisions were taken. Although he moved jobs in early summer, he has been the individual under the most pressure for his role.

Ron Gould's report was commissioned by the Electoral Commission, even though it was liable to share the blame.

He was expected to report in August, but the extent of interviews and the volume of evidence meant a two-month delay in publication.