Nigeria's Senate has thrown out a move to allow President Olusegun Obasanjo to seek a third term in office next year - an issue which has divided the country.
Mr Obasanjo's second term in office ends next year
Opponents shouted for joy as the bill to amend the constitution was rejected.
Supporters of the third term bid spent days in talks trying to acquire a two-thirds majority in parliament.
The BBC's Alex Last says after this devastating blow in the Senate, it appears that Nigeria will be choosing a new president in elections next year.
After a debate, shown live on national television, and a unanimous vote, the senate president said the body would discontinue further proceedings on the bill.
President Olusegun Obasanjo has never said publicly that he would like to remain in office after his current term expires next year.
However, those who had been seeking a third term are pushing to end the current system of two four-year terms for presidents and state governors and see them instead serve one six-year term.
Vice-President Atiku Abubakar would like to stand for president
But for another bill on amending the constitution to be even discussed before elections due early next year, a two-thirds majority would be needed in both houses of parliament and in the state assemblies, which analysts say is unlikely.
"Since it is dead in the Senate, what the House of Representatives is doing now, or would be doing, is an academic exercise," said Senator Victor Ndoma-Egba.
On Monday, Nigeria's anti-corruption agency announced it was investigating claims that MPs have been offered bribes to back moves to let the president seek re-election.
The Economic and Financial Crimes Commission (EFCC) said it was following up claims that MPs had been offered up to 50m naira ($390,000; £206,000).
Vice-President Atiku Abubakar, who wants the top job, had declared himself against the constitutional amendment.
He has helped Mr Obasanjo win two elections and has held the position of vice-president since 1999.
Some opponents of the constitutional change argue that the presidency needs to rotate among people from different regions and ethnic groups.
A prominent financial supporter of President Obasanjo's election campaigns and another former military ruler, General Ibrahim Badamasi Babangida, is tipped as another strong possible candidate.