Abdoulaye Wade won elections in 2000 ending 40 years of Socialist Party rule
Opposition groups in Senegal have expressed concern after MPs voted to extend presidential terms to seven years from five years.
They called for the bill, which needs to be passed by the upper house and president, to be put to a referendum.
It will only come into effect in 2012 when President Abdoulaye Wade is due to step down from office.
Following Mr Wade's 2000 poll victory, the constitution was changed to limit presidents to two terms of five years.
Correspondents say Senegal has enjoyed a rare reputation for stability and democracy in West Africa.
The BBC's Tidiane Sy reports from the capital, Dakar, that local analysts suspect the new changes are part of the plans to groom Mr Wade's son Karim to succeed him.
Mr Wade won elections eight years ago ending 40 years of Socialist Party rule.