The attack Thursday on Mohammed Brahmi of the leftist Popular Current party raised fears of new chaos on the country that unleashed the Arab Spring. Tunisia is on the cusp of enshrining a new constitution meant to lead the way to lasting democracy.
Angry anti-government demonstrations broke out Thursday across Tunisia, with protesters blaming the government of Islamist party Ennahda for the killing.
Unions called a nationwide strike Friday and new protests were expected.
Brahmi's party told The Associated Press it is postponing his funeral, initially planned for Friday, fearing it could inflame supporters on an already tense day.