A woman casts her ballot during a vote to elect a constitution-drafting panel in Benghazi February 20, 2014. [Photo/Agencies]

TRIPOLI - Libyans head to the polls on Thursday to elect a body to draft a new constitution, marking a step in the country's transition after the overthrow of dictator Muammar Gaddafi in 2011.

Western powers hope a peaceful vote will help move the North African country a bit closer towards democracy but it comes at a time of heightened political tensions.

The government of Prime Minister Ali Zeidan is struggling to assert authority and rein in militias who helped topple Gaddafi but kept their weapons to become political players.

Two of the most powerful militias threatened on Tuesday to dissolve the General National Congress (GNC) assembly which they accuse like many ordinary Libyans of paralyzing the country by endless infighting.

On Wednesday the militiamen removed forces they had brought into central Tripoli in a show of force after the United Nations called for restraint, but the incident is a reminder of the country's political fragility.

Libya desperately needs a viable government and system of rule so that it can focus on reconstruction and on healing the divisions opened up by the 2011 war that toppled Gaddafi.

Many normal Libyans are tired of militias and have little trust in political institutions after four decades of quirky one man-rule.

Voter registration was sluggish. More than one million people signed up but this is well below the almost the three million registered for the parliamentary elections in 2012.