Bahaa Hariri declared on Friday he was entering Lebanese politics to follow in the footsteps of his slain father days after his brother, Saad, stepped away from public life.
In a recorded message, Bahaa said he would "continue the journey" of Rafik Hariri, who was assassinated in 2005.
"Through partnership and solidarity, we will enter the battle to take back the country and the sovereignty of the country from its occupiers," said Bahaa.
"The son of the martyr Rafik Hariri will not leave Lebanon, I am with you and very soon I will be among you," he added.