The contact group is the broad-based mediation team that organised a meeting on Tuesday that saw the country's different political camps reach an agreement on sharing jobs in the transitional institutions.
Roindefo also emphasised that the agreement was not signed by the leaders of the different political groups.
Former president Marc Ravalomanana, ousted in March, has already warned that he has no intention of signing the agreement approved Tuesday by his representatives in Antananarivo.
On Friday, transitional president Andry Rajoelina, who would remain in office under the deal, had said he would replace Roindefo with Eugene Mangalaza, an academic acceptable to all parties.
Mangalaza arrived Saturday in Madagascar from Paris.
Roindefo, because of his allegiance to the Rajoelina camp, was unacceptable to the other parties.
The prime minister did not say if he would continue to cling to his post even if the leaders of the four camps -- Rajoelina, Ravalomanana and two former presidents, Didier Ratsiraka et Albert Zafy -- do sign Tuesday's agreement.
He said the most important thing is the setting up of a government that will "just look after the elections," adding that such an arrangement might get the backing of the international community.
He also said he "will run in the presidential election if the rules of the game are clearly defined."
Madagascar has been mired in a political crisis since the start of the year.
After the ouster of Ravalomanana in March an agreement was finally signed in August in Maputo, but the four groups had still not reached an agreement on who was to fill the transitional institution posts.
-------------------------------------------------------------------------------------------------------------------------------