The Education Minister Jan O'Sullivan has said she will not have the money next year to try to tackle class sizes.
Pupil-teacher ratios have increased in recent years with an average class size of 24.4, despite the Government hiring some 2,300 extra teachers in 2013 and 2014.
Jan O'Sullivan told the Dáil any money she has next year will be needed to hire more teachers to deal with rising numbers of school children.
"This is a very significant investment at a time of scarce resources. My focus has to be on seeking the funding necessary to meet this demographic growth and not on additional spending measures," she said.
"If in future years there is funding available to reduce class size, my preference is that it would be targeted at reducing class size in the infant years."