TUNIS, Tunisia -- Tunisia's prime minister says the government will not step down despite opposition demands. He also promises to finish the constitution by October and hold elections on Dec. 17.

Ali Larayedh gave a defiant press conference Monday that made clear the Islamist-led government would not give in to the mounting calls to dissolve the elected assembly and form a national unity government following a political assassination.

Thursday's slaying of leftist politician Mohammed Brahmi plunged the country into a political crisis, with the opposition calling it a sign of the government's failure.

As the birthplace of the Arab Spring, Tunisia's democratic transition is being closely followed.