At a press conference in Dublin, the group said the Minister for Education, Mary Hanafin, should give a pledge to reduce the average class size by at least one point this year, from its current level of 24.2 children per teacher, and again by a further one point each year for the next five years as a minimum.
The TDs say they support the Irish National Teachers' Organisation campaign to highlight what they say is the Government's failure in this area.
They claim measures must be put in place immediately to address educational disadvantage, and ensure equal access to education and equal opportunities for the future.
The TDs supporting the campaign are Joe Higgins, Paudge Connolly, Paddy McHugh, Dr Jerry Cowley, Tony Gregory, Finian McGrath, James Breen, Catherine Murphy and Seamus Healy.
