Montenegro was part of the former Yugoslavia and then in a union with Serbia before declaring independence in 2006. The country joined NATO in 2017, defying opposition from traditional Slavic ally Russia, and wants to become part of the European Union next.
Opposition parties have accused Djukanovic of corruption and crime. Pro-Serb parties and Serbia have complained of alleged pressure in Montenegro on the rights of ethnic Serbs and the Serbian church.
The last election in October 2016 was marked by a foiled coup attempt that Montenegrin authorities alleged included plans to assassinate Djukanovic to block Montenegro’s NATO membership.
Two former Russian military intelligence agents and about a dozen others have been convicted of the plot. Russia has denied involvement.
Voters will also choose candidates to fill local government offices on Aug. 30.