Obasanjo, who arrived in the capital of Dakar in his role as head of a joint African Union-Economic Community of West African States observer mission, is to meet with leaders of the opposition 23 June Movement, known as M23, the BBC reported.
M23 has organized protests nationwide against President Abdoulaye Wade's candidacy for a third term, which his rivals say is illegal.
Six people have been killed in recent violent protests.
Obasanjo also is to meet presidential candidates, including two former prime ministers, Moustapha Niasse and Idrissa Seck, and the leader of the opposition Socialist Party, Ousmane Tanor Dieng.
The BBC noted Senegal is often cited as a model African democracy as the only West African country where the army has not seized power.
Protests erupted in January after the country's highest court ruled Wade, 85, could seek a third term, despite the two-term limit mandated in the constitution, and barred singer Youssou Ndour from running.