The People's Committee for Political Reform in Tonga says it hopes to present a petition calling for a new Prime Minister to the King this afternoon.
The document, thought to have between 5,000-6,000 signatures, follows an earlier petition by the Tongan Women's National Congress, also seeking a change of leadership.
The committee's petition was launched after the sinking of the Princess Ashika, in which 74 people were killed.
Congress members are 11 days into protest fasting over the handling of the Ashika disaster and other issues, including rising crime against women and children.
The number two People's Representative and a member of the committee, Isileli Pulu, says the two organisations are supporting each other.
"We are hoping that the King will make a wise decision on how to handle this because this is not the first time for us to submit a petition for the Prime Minister to resign and hopefully the King will concede our petitions and act likewise."
Isileli Pulu of Tonga's People's Committee for Political Reform.