Four leaders representing West African regional bloc ECOWAS and the African Union are due to meet with Gbagbo to ask him to give up the presidency after a November 28 poll that internationally recognised results showed he lost to Ouattara.
More than 170 people have been killed since the start of the standoff in the world’s top cocoa grower, which threatens to restart open conflict in the country still split in two by a 2002-03 civil war.
Gbagbo, who has the backing of the country’s top court and the army, has shrugged off pressure to step down and said on state television over the weekend that Ouattara "should not count on foreign armies to come and make him president".
A Gbagbo spokesman said Gbagbo, who has been in power since 2000, would not agree to leave.
Ivory Coast’s constitutional court, run by a staunch Gbagbo ally, reversed the U.N.-ratified electoral commission results showing a Ouattara win, citing massive evidence of fraud.
As the political crisis deepened, Ivory Coast missed a nearly $30 million interest payment on its $2.3 billion Eurobond
that was due on Friday, the chair of the London Club of commercial creditors told Reuters on Monday.
But Thierry Desjardins, London Club chair and senior vice president of debt restructuring at BNP Paribas, added: "There is a grace period of 30 days, they are not in default."
Three west African heads of state — Benin’s Boni Yayi, Sierra Leone’s Ernest Bai Koroma and Cape Verde’s Pedro Pires — were due to return to Abidjan on Monday after an initial trip last week failed to convince Gbagbo to step down.
Kenyan Prime Minister Raila Odinga will join them. By late morning, only Odinga had arrived in Abidjan.
"He will be the voice of the African Union," according to a statement issued by Odinga’s office.
"He will seek a peaceful settlement to the election crisis (…) and seek an assurance of safety and security for Mr. Laurent Gbagbo and his supporters, if he agrees to cede power."
The United States and the European Union have imposed a travel ban on Gbagbo and his inner circle, while the World Bank and the regional West African central bank have frozen his finances in an attempt to weaken his grip on power.
If military forces are eventually sent in by ECOWAS, it may trigger open conflict between Gbagbo’s government army and the ECOWAS force. Northern rebels who tried to topple Gbagbo in 2002 have said they would also get involved.
Ouattara’s camp say the army is divided and most troops would put up little resistance to a sufficient display of force.
But West African leaders are seen as unlikely to carry through the threat of force because of the risk of being bogged down in an urban war. They are also believed to lack the operational intelligence to track Gbagbo and his supporters down in a strike.
Nigeria, with the region’s biggest army, has its own growing security issues at home and its own elections in April.
The United Nations has said Gbagbo may be criminally responsible for human rights violations, including killings and kidnappings by security forces since the election.
Ouattara’s Prime Minister Guillaume Soro, confined with the rest of Ouattara’s rival government to the lagoon-side Golf Hotel under the protection of 600 U.N. troops, told reporters at the weekend that Gbagbo has only days to leave power peacefully.
The message the African neighbours were bringing "seems clear", he said. "This is the last chance for Mr. Gbagbo to get a peaceful departure from power and a guarantee of immunity."
Fears of an escalation of violence have led more than 18,000 people to leave Ivory Coast for neighbouring Liberia, according to the United Nations.
Cocoa output from the top producer nation is running near even with last year, but exporters warned that if the standoff turns violent, it could pose a big threat to shipments for the rest of the season.