By Camillus Eboh and Nick Tattersall
ABUJA/LAGOS (Reuters) - Nigeria's two main opposition parties have failed to reach an eleventh-hour alliance to unseat President Goodluck Jonathan, leaving them divided ahead of elections in three days time.
Officials from the Congress for Progressive Change (CPC) and the Action Congress of Nigeria (ACN) held hours of talks late into Tuesday night and again Wednesday on the possibility of fielding a single candidate against Jonathan.
"While it is true that representatives of both parties have been engaged in talks aimed at forging an alliance ... we regret to announce that such talks have not led to any alliance," ACN chairman Bisi Akande told a news conference in Abuja.
"We have decided ... it is better for each of the parties to go into the presidential election on his own platform. If at the end of the election Saturday there is no clear winner, we will make a decision on which way to go," he said.
Options under discussion had included former anti-corruption chief Nuhu Ribadu, the ACN presidential candidate, stepping down and supporting the candidacy of former military ruler Muhammadu Buhari of the CPC, opposition sources said.
There were significant hurdles to any deal, not least selling it to the respective party faithful just days before the election. It is already too late to re-print ballot papers and any agreement could have backfired by creating confusion.
"There may be time to complete a deal but not to sell a deal," said one opposition source who declined to be named.
The ruling People's Democratic Party (PDP) has won every presidential race since the end of military rule in 1999 and Jonathan is considered the favorite, but the opposition parties are hoping their regional strengths could force a run-off.
Buhari has strong support in parts of the mostly Muslim north while the ACN has its stronghold in the southwest.
More than a dozen candidates are vying for the presidency, but Jonathan, Buhari and Ribadu are the main contenders.
Last Saturday's parliamentary polls, in which the ACN gained seats but the CPC perform less strongly than expected in some areas, further complicated the chances of an opposition pact.
Sources said one possible arrangement discussed prior to the parliamentary vote had been for the opposition party that won the most seats to field the presidential candidate. That would have meant Ribadu leading the opposition charge.
But Buhari -- who ruled Nigeria from 1983 to 1985 -- is much more of a political heavyweight than Ribadu, the youngest of the main presidential candidates.
The PDP -- which has dominated Nigerian politics since 1999 -- lost ground in the parliamentary vote, considered by observers to have been the most credible in Nigeria for decades. Based on results released so far, its majority in the lower house could slip to just over half from three quarters.
The opposition is hoping that momentum could carry it through to a strong showing in the presidential election and governorship votes in the 36 states a week later.
But it faces an uphill struggle.
Jonathan needs to secure an absolute majority and at least a quarter of the vote in two thirds of the states to win in the first round. The PDP has the national machinery to achieve that, while the opposition parties are essentially regional players.
(Writing by Nick Tattersall, editing by )