TUNIS - Tunisians are likely to vote for their first full post-revolutionary parliament in just under a year's time, a government official told Reuters on Saturday.Since elections that followed the overthrow of the autocrat Zine al-Abidine Ben Ali, an uprising that sparked revolutions across the region, Tunisia has been governed by an interim assembly whose main task is to draft a new constitution within about a year.Lutfi Zaitoun, political adviser to Prime Minister Hamadi Jbeli of the moderate Islamist party Ennahda that won October's election, said its work should be completed in time for a full election to be held in mid-March 2013."There is an agreement between the parties in the ruling troika to set a road map (for elections) to reassure public opinion and domestic and foreign investors," he said."March 20 of next year has been suggested. It is not a final date 100 percent, and could happen weeks earlier if we finish drafting the constitution."For now, Ennahda is ruling in coalition with two secular parties, Ettakatol and Conference for a Republic.