ABIDJAN, Ivory Coast (AP) -- Surrounded by troops backing Ivory Coast's democratically elected leader, strongman Laurent Gbagbo huddled in a bunker at his home with his family Tuesday and tried to negotiate terms of surrender, officials said.

The Skanner News Video: UN and French forces launch assault; Gbagbo negotiating surrender

Forces loyal to Alassane Ouattara (pictured at left) have seized the presidential residence where Gbagbo tried to wrest last-ditch concessions, said a senior diplomat who spoke on condition of anonymity because of the sensitivity of the matter. He also said Gbagbo's closest adviser and longtime friend had abandoned him, leaving the bunker for the French ambassador's home.

Ouattara, who Ivory Coast's electoral commission and the United Nations said won the November elections, has urged forces loyal to him to take Gbagbo alive.

The Skanner News Video: Civilians Flee Abidjan

United Nations and French forces opened fire with attack helicopters on Gbagbo's arms stockpiles and bases on Monday after four months of political deadlock in the former French colony in West Africa. Columns of foot soldiers allied with Ouattara also finally pierced the city limits of Abidjan.

"One might think that we are getting to the end of the crisis," Hamadoun Toure, spokesman for the U.N. mission to Ivory Coast said by phone. "We spoke to his close aides, some had already defected, some are ready to stop fighting. He is alone now, he is in his bunker with a handful of supporters and family members. So is he going to last or not? I don't know."

Toure said that the U.N. had received phone calls Tuesday from the three main Gbagbo-allied generals, saying they were planning to order their troops to stop fighting.

"They asked us to accept arms and ammunition from the troops and to provide them protection," he said.

French Defense Minister Gerard Longuet told a Paris news conference Tuesday that he hoped the situation would be resolved within hours. French Foreign Minister Alain Juppe also told French lawmakers that he believed Gbagbo's departure is near.

The offensive that began Monday included air attacks on the presidential residence and three strategic military garrisons, marking an unprecedented escalation in the international community's efforts to oust Gbagbo, as pro-0uattara fighters pushed their way to the heart of the city to reach Gbagbo's home.

President Barack Obama said Tuesday he welcomed the role of the U.N. and French forces in Ivory Coast, also known by its French name Cote d'Ivoire.

"To end this violence and prevent more bloodshed, former President Gbagbo must stand down immediately, and direct those who are fighting on his behalf to lay down their arms," Obama said in a statement. "Every day that the fighting persists will bring more suffering, and further delay the future of peace and prosperity that the people of Cote d'Ivoire deserve."

Gbagbo refused to cede power to Ouattara even as the world's largest cocoa producer teetered on the brink of all-out civil war as the political crisis drew out, with both men claiming the presidency. Ouattara has tried to rule from a lagoonside hotel.

"Gbagbo is exploring different options for turning himself in," Ouattara spokesman Patrick Achi said Tuesday. "He has been in touch with different leaders involved in this crisis."

A Paris-based lawyer who has represented Gbagbo's government denied that Gbagbo's foreign minister, Alcide Djedje, had abandoned his close friend but said he had gone to the French Embassy to protest Monday's attacks by French and U.N. forces.

"He has absolutely not resigned and is currently being scandalously held against his will," attorney Lucie Bourthoumieux said in a statement.

Even before the offensive, postelection violence had left hundreds dead - most of them Ouattara supporters - and forced up to 1 million people to flee their homes.

Ivory Coast gained independence from France in 1960, and some 20,000 French citizens still lived there when a brief civil war broke out in 2002. French troops were then tasked by the U.N. with monitoring a cease-fire and protecting foreign nationals in Ivory Coast, which was once an economic star and is still one of the only countries in the region with four-lane highways, skyscrapers, escalators and wine bars.

Following four months of attempts to negotiate Gbagbo's departure, the U.N. Security Council unanimously passed an especially strong resolution giving the 12,000-strong peacekeeping operation the right "to use all necessary means to carry out its mandate to protect civilians under imminent threat of physical violence ... including to prevent the use of heavy weapons against the civilian population."