For the crowded field of opposition candidates aiming to take control of the main cities, the elections are seen as a test of strength ahead of a legislative election in June and the battle for the presidency in 2024.

Some opposition parties have formed a coalition aiming to head off any attempt by Sall, whose tenure has been plagued by accusations that he unjustly torpedoes political challengers, to seek a third term in power.

"At stake in a broad sense for the political parties as well as coalitions of political parties is that, in the absence of opinion polls... the territorial elections on Sunday are kind of primaries for the 2024 presidential election," said Ousmane Khouma of Dakar's Cheikh Anta Diop University.

Sall, 60, came to power in 2012 and won re-election in 2019.

He has not ruled out seeking a third term following a constitutional referendum in 2016 that could be used to reset the clock on his term of office. Similar constitutional devices were used by Guinea's ousted President Alpha Conde and Alassane Ouattara of Ivory Coast to run again despite violent protests in both countries.

Around 6.6 million voters are expected to vote at more than 15,000 polling stations.

The biggest prize is the capital, Dakar, currently in the hands of the opposition, where the ruling party coalition list is led by Senegal's Health Minister Abdoulaye Diouf Sarr.

He will face six opposition lists that include those led by outgoing mayor Soham El Wardini, the first woman to lead the city, and popular opposition mayor of the Dakar Mermoz municipality Barthelemy Dias.

Dias, is in a coalition with 47-year-old firebrand opposition leader Ousmane Sonko, who came third in the 2019 presidential election and is seen as a potential challenger in 2024.

Sonko is leading the opposition charge to take the southern city of Ziguinchor, capital of the Casamance area of Senegal.

His arrest last year following a rape accusation, which he denied, sparked days of violent protests and stoked fears that President Sall was interfering with the judiciary to target potential challengers. read more

"The change we want in the 2024 presidential election starts on January 23, 2022," Sonko told a recent campaign rally.

Reporting by Bate Felix; Editing by Alex Richardson