(CNN) Millions of Venezuelans have voted to reject President Nicolas Maduro's controversial plans to rewrite the country's constitution. Nearly 7.2 million Venezuelans took part in the non-binding referendum organized by the country's main opposition parties, with the overwhelming majority of voters coming out against Maduro's plan. Venezuela is in the grip of social unrest, which has paralyzed the country amid violent protests seeking government reform. The government has condemned the referendum as illegal, and has instead called for a July 30 vote to elect a special assembly to rewrite the 1999 constitution. Referendum results The referendum asked voters three yes-no questions. More than 98% of voters chose to reject the proposed constitutional assembly; request the military defend the existing constitution; and support fresh elections before Maduro's term ends in 2019.