A Nigerian ruling party official says the legal challenge against President Umaru Yar'Adua's election is a distraction and should be dropped. From the Nigerian capital, Abuja, Gilbert da Costa reports the two leading opposition presidential candidates have come under pressure to withdraw their suits.

 The lawsuits by former military ruler Muhammadu Buhari and ex President Atiku Abubakar seek a court annulment of last April's presidential election. The opposition candidates say the vote was rigged in favor of their main rival, President Umaru Yar'Adua.

All three candidates are Muslims from the north of the country.

The ruling Peoples Democratic Party national executive member, Abdullahi Jalo, says the overall political interest of the homogenous north would best be served by the discontinuation of the legal challenge to Mr. Yar'Adua's election.

"The mounting pressure on Buhari and Atiku, it is our culture. We the northerners, we are one family," said Jalo. "We do not want people to infiltrate us. This is our culture in the north. We do not fight against ourselves. If we quarrel, we go and sit down and settle. That is the position."

April's polls marked the first democratic handover of power from one elected president to another in Africa's most populous country.

But fraud, violence and intimidation were so widespread election monitors dismissed the process as a charade.

European Union observers said the elections "fell far below basic international standard" and were not "credible."

Analysts say Mr. Buhari and Mr. Abubakar have resisted pressures, intimidation and frustrations to pursue their challenge and would likely see the process through to the every end.

Mr. Buhari's spokesman Osita Okechukwu says the former military ruler is keen to expose the electoral fraud in the interest of Nigeria's democracy.

"The issue is not about the north. It is about democracy, the sanctity of the ballot box, the people's inalienable right to elect their leaders and not the imposition of leadership," said Okechukwu. "The world cannot be wrong that the April election was flawed. Nobody can wish it away. We have implicit confidence in the judiciary."

President Yar'Adua has acknowledged the election was flawed but said he believed he had the mandate of the Nigerian people.

He also set up a 21-member panel to reform Nigeria's electoral system.