Tunisia's national assembly on Friday began voting on the long-delayed new constitution, which must be adopted by January 14, the third anniversary of the 2011 revolution.
Politicians voted to approve the title of the charter, which will now be voted on article by article.
They are due to examine the text's preamble, before scrutinising its 150 articles and 225 proposed amendments.
For the constitution to be adopted, it must be approved by two thirds of the national assembly's 217 elected members or put to a referendum. An agreement would represent a crucial milestone in the country's democratic transition.
It has taken more than two years to draft the text, mainly due to disagreements between the ruling Islamist party, Ennahda, and opposition groups.
Its adoption should also end a political impasse that has gripped the country since the killing of an opposition MP in July by members of an armed group.