Nigeria's vice-president has said that the Senate decision to throw out a bill which would have let the president seek re-election will strengthen democracy.
Mr Abubakar said third term opponents had been threatened
"The decision is one of the best things to happen to Nigeria," said Atiku Abubakar, who wants to contest next year's elections himself.
The question of allowing President Olusegun Obasanjo a third term has divided Nigeria and the ruling party.
Nigeria had many years of military rule until Mr Obasanjo was elected in 1999.
Mr Obasanjo has not publicly said whether he wanted to remain in office but the BBC's Alex Last in Lagos says it now appears that Nigeria will have a new president next year.
Our correspondent says there is "shock and disbelief" around the presidential camp.
Mr Obasanjo's special advisor on the National Assembly Senator Florence Ita-Giwa told the BBC's Network Africa programme that the president had been consulting with party leaders.
"He had no intention of staying if he is not wanted," she said, adding that it was a shame that the third term issue had overshadowed many other constitutional amendments in the bill.
Those opposed to changing the constitution had claimed that they had been offered bribes and threatened to change their minds.
"It confirms that democracy has a teeming army of believers and converts, who will defend it even in the face of inducement, blackmail, harassment, threat and intimidation," Mr Abubakar said following the Senate's decision.
Human rights lawyer Gani Fawehinmi, who contested the 2003 elections, said he was "delighted" by the news.
Mr Obasanjo's second term in office ends next year
"Obasanjo's dream has been killed. It is the end of a sit-tight rule in Nigeria, political robbery and gangsterism," he told the AFP news agency.
"Democracy has triumphed over dictatorship."
Our correspondent says some people say the government may try again to change the constitution but all the politicians and analysts he has spoken to say there is no way back.
The announcement that the bill had been defeated was greeted with shouts of joy in the Senate.
Nigeria will now have several months of an exciting and interesting power-struggle ahead of next year's elections, our correspondent says.
Mr Obasanjo is a Christian from the south-west and people in other parts of the country believe the country's top job should rotate between the regions.
Mr Abubakar is a northern Muslim, like another man seen as a strong candidate, former military ruler General Ibrahim Babangida.
He also welcomed the vote, saying he knew the moves would not succeed because there had not been "adequate consultation".
But Alex Last says that many in the oil-producing south and the south-east - regions which have never produced a Nigerian president - feel it should be their turn.