Children in Scotland is lobbying the education committee of the Scottish Parliament for an initial expansion of the current service - five free half-days a week for all three and four-year-olds - to a full-time whole-day place for all children in the two years before they start school.
The organisation argues that this should only be the first step towards a more radical extension of early years care and education. This would culminate in an entitlement for all children to a place in pre-school from the age of one and to out-of-school care for all children aged 12 and under.
Pre-school and after-school places should be either free or subsidised according to parent income, Shelley Gray, policy officer for Children in Scotland, said.
The submission from Children in Scotland to the education committee's early years inquiry - which will start taking oral evidence this month - bases its argument on recent research it carried out comparing Scotland with England and Sweden.
"Whilst Sweden has created a universal service for children aged one to 12 years, based on what the OECD describes as 'a strong but equal relationship' between schools and pre-school and school-age childcare services, progress in Scotland and England has been much more limited," it states.
While arguing that leave provision and flexible working should be enhanced for parents so that they can care for their children themselves for a longer period, Children in Scotland also calls for early years policy to respond to the increase in maternal employment.
In common with other submissions, it points to key findings from the EPPE (Effective Pre-school and Primary Education) project - Europe's largest pre-school research project, which was carried out in England - that there is a direct correlation between the quality of a pre-school setting and qualifications of staff.
The inquiry seems likely to reignite the debate about qualifications and salaries of early years workers - and whether pre-school services should be led by teachers. Children in Scotland states: "It is acknowledged that the early years sector is generally under-qualified and underpaid."
West Lothian Council also quotes the EPPE project in its submission, saying that it is committed to retaining teachers in all pre-school education provision.
It draws particular attention to the EPPE findings: "Having qualified trained teachers working with children in pre-school settings . . . had the greatest impact on quality and was linked specifically with better outcomes in pre-reading and social development."
Cath Boyle, education officer in West Lothian, stressed the importance of learning through play and commends European examples of formal education being delayed until the age of six.
"In order to maintain appropriate numbers of well-qualified early years specialists, consideration should be given to including more pre-school experience in initial teacher training. Although pre-school education provision has expanded over the past few years, teacher supply, with appropriate expertise, does not appear to have kept pace."
Amanda Nicholls, vice-chairman of Tillicoultry primary school board, has written to the committee protesting at proposals by Clackmannanshire Council to replace nursery teaching staff with an early years worker - a move she claims is cost-driven.
Laura Henderson, a fourth-year BEd student at Strathclyde University, wrote to the committee on behalf of six fellow students, stating: "We believe children of three are too young to begin nursery school. Their social skills and communication skills are not developed enough to interact properly and engage in the activities required of them. At this age they still need mothering and fun and an educational setting does not really provide for their needs."