Zambians are forming long lines at polling stations in a tight election race for president and parliament that has been marred by violence between rival factions.

There were no early reports of unrest during voting Thursday in a country whose peaceful transitions of power in the past have been held up as a democratic model in Africa. However, officials anticipate tension after the close of voting and the final announcement of results: A winner must win more than 50 percent to avoid a runoff election.

President Edgar Lungu of the ruling Patriotic Front party faces businessman Hakainde Hichilema of the opposition United Party for National Development.

Final results are expected within 48 hours after polling stations close.