Comes despite armed forces' ouster of democratically-elected president.
Secular independent Education Minister Salem Labyedh has resigned amid political crisis.
Will redeploy the forces to help fight its own homegrown Islamist insurgency.
Proposal for 50th anniversary of independence provokes outrage.
Ennahda party has faced pressure in wake of two assasinations.
Army captain publicly questioned Muhoozi Kainerugaba over military promotions.
"If Ennahda refuses this suggestion, we will withdraw from government," said Ettakatol leader.
Same weapon used in the earlier killing of another leftist leader.
Allows U.S. to keep up $1.5 billion in annual military and economic aid to Arab World's most populous country.
Mohammed Brahmi, an Arab nationalist , was killed in his car outside his home.