The controversial pupil premium should be established in Wales to help bridge the education funding gap with England, according to the Liberal Democrats.
Jenny Randerson, the party's education spokeswoman, said the pound;2.5 billion fund, announced in the Westminster government's comprehensive spending review (CSR) last week, should be the basis of a similar scheme in Wales.
She said it would allow schools to give more effective help to poorer pupils and claimed that without it the pound;527 per pupil funding gap with England would widen further.
But the Westminster government has been forced to admit that the pound;2.5 billion earmarked for the pupil premium, which is the key Lib Dem policy in the coalition agreement, is not new money, prompting Labour to dub it a "con".
But Ms Randerson, who is stepping down as an Assembly Member after next May's election, told TES Cymru it was vital that extra resources were targeted at the poorest Welsh pupils.
"There is a spending gap with England already and the pupil premium in England alone will just widen the gap," she said.
"Whilst the pupil premium will have to be based upon who gets free school meals initially, later it can be more accurately targeted through the tax system," she added. "The premium would mean schools would be able to help children from poorer homes much more effectively."
Ms Randerson claimed Welsh headteachers would "rise to the challenge" of having the money passported directly through to them to spend on pupils as they saw fit.
However, she dismissed the Coalition's other key education policies of free schools and academies as "irrelevant" for Wales.
"Academies would be extremely difficult to implement in rural areas, if not impossible," she said. "They are a sideshow; a way of turning round schools that are not achieving, but not fundamental to how schools are run.
"What I would take from the free school approach is more local control for decision-making.
"Teachers and parents in Wales would welcome less government interference and more freedom to decide what they want from their education system."
An Assembly government taskforce is currently looking at the structure of education services in Wales, including what can be delivered locally and what can be devolved to schools.
Ms Randerson said the pupil premium would give schools the choice of what services they want to provide for their pupils.
But Iwan Guy, interim director of heads' union NAHT Cymru, said: "There are divided views on this. While heads of larger primaries and secondaries would welcome extra freedoms and a greater deal of autonomy, smaller schools don't have the capacity or the support staff to handle it."
Despite this, Ms Randerson is sure her approach would be welcomed. "All politicians have the same aims; we all want to raise attainment of those who are doing the least well and increase the level of skills and qualifications throughout the system," she said.
"But our approach is much more localised - trust local people with decision-making. The LabourPlaid government has a centralised approach. Every time a school fails their solution is to take more control to the centre."