"The reforms were imposed by the monarchy, there was not a constitutional assembly composed by members of the civil society," he said, sitting in the headquarters of the union in central Rabat.
King Mohammed VI announced the reforms, meant to curb the power of the 300-year-old dynasty, in an historic March 9 speech as protests were sweeping his country and the broader Arab world.
Some see the proposed reforms as opening a new chapter of the Arab Spring in which the regime, with no bullets or teargas, introduces changes itself.
The European Union said the reform initiative "signals a clear commitment to democracy." Prominent Western analysts have hailed the changes as a new beginning.
"What's so important about what the Moroccan king has done is that he is forging a different model of change in the Arab world," wrote Kenneth M. Pollack recently for the Washington-based Brookings Institution, where he is the director of the Saban Center for Middle East Policy.
Mohammed Ziane, the founder of the Moroccan Liberal Party, supported the reforms with enthusiasm, linking the changes in Morocco with regional events. "This is a beginning," he says on the phone from Casablanca. "Moroccans and the populations of the region finally started thinking about democracy, asking to have more control on their governments."
But some opposition leaders were not impressed by the proposed changes, and urged the population to boycott Friday's vote.
Those calling for a boycott came together under the umbrella of the February 20 movement - named for the day of the first anti-regime demonstration.