The National Salvation Front issued a statement on Sunday evening in which it rejected Egypt's scheduled constitutional referendum slated for Saturday, 15 December.
"The National Salvation Front has decided not to recognise the upcoming referendum and the draft constitution, which it considers farcical," the statement read. It added that holding the referendum at this particular juncture – following Wednesday clashes outside the presidential palace in Cairo – would only further polarise Egyptian society.
"The draft constitution does not reflect the hopes and aspirations of the Egyptian people following the January 25 Revolution," the statement read, going on to claim that the proposed charter enforced "presidential dictatorship" and neglected the "social and economic needs" of the Egyptian people.
The front, an umbrella grouping of liberal, leftist and nationalist parties, also slammed a Sunday decision by President Mohamed Morsi to raise sales taxes on several commodities.
The front went on to call for a million-man protest on Tuesday in public squares across the country as a means of escalating against the draft constitution and scheduled referendum.
The Coalition of Islamic Forces, meanwhile, which includes several Egyptian Islamist parties and groups, has called for a two-million-man counter-rally on Tuesday under the banner "Yes to legitimacy."