Sall and Moustapha Niasse are the leading contenders in the campaign to unseat the 85-year-old Wade, Voice of America reported Friday.
Senegal's Constitutional Council ruled Sunday that Wade could seek a third term, despite the two-term limit mandated in the constitution.
Senegalese political analysts say dividing the opposition between Sall and Niasse will only help Wade's re-election efforts, VOA reported.
Amnesty International called on the president to rein in security forces after three people were killed and dozens injured in two days of political demonstrations against the council ruling.
A protester was killed Tuesday in Dakar when a police vehicle plowed into a group of anti-Wade protesters.
"President Wade must send a clear order to his security forces not to resort to lethal force unless their lives are in danger," Salvatore Sagues, Amnesty International's researcher on West Africa, said Wednesday in a statement.