The People's Movement say a power grab by Europe's biggest countries will come into force next month.
Under the Lisbon Treaty the voting rights of countries in the Council of Ministers will be decided on by population from November 1st.
Ireland's will be more than halved from two percent to nought-point-eight, while Germany's will double from eight to sixteen percent.
The group held a conference at Buswell's Hotel today which Thomas Pringle and former MEP Patricia McKenna attended.
Our reporter, Paraic Gallagher, spoke to the People's Movement today:
Thomas Pringle also spoke at the event: