Tunisia's moderate Islamist party appears headed for victory in Sunday's election, the first free election resulting from the Arab Spring which has seen despotic governments topple across North Africa and the Middle East.

Although official results have yet to be announced, provisional results give the Ennahdha party about 40 percent of the vote.

Voters were electing a 217-seat constituent assembly that will draw up a new constitution. The assembly will be charged with determining the system of government and ensuring civil liberties. In the meantime, it will also appoint a caretaker government.

A large turnout has been reported. Tunisia's independent electoral commission said more than 90 percent of the 4.1 million registered voters cast ballots. They were allowed to choose among multiple political parties for the first time since independence in 1956. In previous votes, only ruling party members were allowed to run.

Former Peruvian President Alejandro Toledo was among thousands of international and domestic observers. He called the vote not only free and fair but exemplary.

U.N. Secretary-General Ban Ki-moon, in a message of congratulations on Sunday, said the election is a significant development in the democratic transition of the region.

The Islamist Ennahdha party has already taken steps to form a coalition that would model a government after the secular, pluralist democracy in Turkey, whose ruling party also has an Islamic identity.

Election observers predict that women could capture nearly one third of the seats in the constituent assembly, a far larger proportion than in any Arab country.

But there is concern that Ennahdha could reverse some of the progress in women's rights that has been made in Tunisia.

This first vote of the Arab Spring came a little more than nine months after Tunisians overthrew longtime dictator Zine el Abidine Ben Ali.

U.S. President Barack Obama has offered his congratulations, saying Tunisia has “changed the course of history” and “inspired the world.”