At the center of the storm is President Abdoulaye Wade, who is officially 85 but probably older, as proper birth records were not kept by the French colonial authorities. Mr. Wade, a French-trained lawyer with degrees in economics and mathematics, is among the world’s oldest leaders, and he is determined not to retire anytime soon.

Seeking what his opponents consider an illegal third term, Mr. Wade mocks the critics as lacking the vigor he displays, while regularly haranguing diplomats and other visitors for hours about the finer points of the country’s laws, principles of economics and his aesthetic theories.

Opponents sputter in rage against what they regard as the elderly president’s upending of the long respect for law displayed in this impoverished but proud country of 12.5 million, which is dependent on foreign aid, fishing, peanuts and phosphate. Senegal was the first to send an African to the French National Assembly in 1914 and one of the rare African countries never to have had a military coup.

Those who have worked for Mr. Wade suggest that the electoral conflict is rooted in his penchant for frequently shuffling his cabinet (he has had nearly 200 ministers, said one of his six former prime ministers, Macky Sall), tinkering with his country’s Constitution and revising his grandiose, often unrealized development plans.