The Constitutional Council upheld its Friday decision to allow the 85-year-old Wade to run in the February 26 election, a ruling that sparked deadly weekend riots in the normally placid west African nation.
The council's "five wise men" said early Monday that appeals against their ruling were "unfounded" but also rejected Wade's own challenge against the inclusion of three other candidates in next month's presidential race.
The opposition argues that the constitution allows a president to serve only two consecutive terms, but Wade says the law, which was amended in 2008, does not apply retroactively and cannot take into account his previous two terms.
Senegal's international music icon Youssou Ndour, whose own plans to stand were rejected by the council, branded its ruling on Wade as "shameful" and the last step in a "constitutional coup d'etat".
"Senegal is ashamed. Senegal is bruised," said the singer, whose appeal against his exclusion was also dismissed by the council.
"We have been betrayed by this shameful decision" said Ndour, urging African nations and the international community to protest.
The opposition, united under the June 23 Movement (M23), warned Sunday that "the time for talking is over" as it called for mass resistance and a rally in the coming days.
"This is an appeal, a solemn, strong and resolute appeal to engage in resistance. We are ready for all sacrifices," said Amadou Gueye, one of the movement's leaders.
Senegal, often hailed for its vibrant democracy, was rocked by riots on Friday night when a rally erupted in anger after the council gave Wade the green light.
A policeman was killed when angry youths engaged in running battles with police, torched cars and shops, erected barricades and burned tyres on Dakar's main roads.
"Our main concern is not the election right now, it is standing alongside our people," said ex-foreign minister and presidential candidate Cheikh Tidiane Gadio.
When Wade was elected in 2000 for a seven-year mandate, there was no limit on the number of presidential terms. He was re-elected in 2007 after introducing a two-term limit and reducing the mandate to five years.
But Wade again revised the constitution the following year, reverting to a seven-year mandate, renewable once. Wade argues that he is entitled to two fresh terms from 2012, but the opposition disagrees.
