The Minister for Education, Ruairi Quinn, is being asked to extend the new school textbook rental scheme.
The Minister is launching grants for primary schools which do not already have such a scheme in place - but is facing calls to extend it to those schools which made sacrifices to set up their own scheme already.
"The costs at primary are somewhat less than the costs in secondary [for books]," said INTO President Brendan O'Sullivan.
"I think it wouldn't take a huge amount of money … to extend the scheme to include all of the schools that have rental schemes. People have had to make savings elsewhere in order to set up their own schemes."
But Ruairi Quinn said this is about helping hard-pressed parents with book costs.
"this was not about the schools themselves - this was about parents and children.
"Yes, some people who did put in a lot of effort have now found that they have missed out on this particular initiative, but [it] was to close the gap."
Currently, around three quarters of primary schools operate a textbook rental system.