TRIPOLI, Libya — Forty years after he seized power in a bloodless coup d’état, Col. Muammar el-Qaddafi, the Libyan leader once called the mad dog of the Middle East by President Ronald Reagan, has achieved the international status he always craved, as chairman of the African Union.

Colonel Qaddafi’s selection last month to lead the 53-nation African Union coincided with his emergence as a welcomed figure in Western capitals, where heads of state are eager to tap Libya’s vast oil and gas reserves and to gain access to virgin Libyan markets. Once vilified for promoting state terrorism, Colonel Qaddafi is now courted.

But Colonel Qaddafi remains the same eccentric, unpredictable revolutionary as always. He has used his new status to promote his call for a United States of Africa, with one passport, one military and one currency. He has blamed Israel for the conflict in the Darfur region of Sudan, defended Somali pirates for fighting “greedy Western nations” and declared that multiparty democracy was not right for the people of Africa.

“This is a role that Qaddafi has been looking for for 40 years,” said Wahid Abdel Meguid, deputy director of Egypt’s largest research institute, the government-financed Ahram Center for Political and Strategic Studies. “He kept shifting and changing directions in search of this role.”

Each step of Colonel Qaddafi’s calculated transformation from terrorist sponsor to would-be statesman has bolstered the next. The thaw in relations with the West, which began in 2003 when he gave up Libya’s nuclear weapons program, gave him more credibility in Africa; and his rising status in Africa has made him more acceptable to the West. All of which has been aimed at one primary objective: bolstering his image.

At one time, Colonel Qaddafi, who was born in 1942, tried to position himself as the next pan-Arab leader. But he was rejected, at times mocked, for his eccentric style and pronouncements. His country was isolated for decades because he sent his agents to kill civilians, including in the bombing of Pan Am Flight 103 over Lockerbie, Scotland, in 1988.

But now in Africa, he has found traction. African heads of state view him suspiciously, and his one-Africa agenda is generally dismissed as unworkable. But he is embraced for his growing status in the West, the lack of credible alternatives across the continent and his money. Many stories are told in Tripoli of African leaders visiting Colonel Qaddafi and leaving with suitcases full of cash, stories that cannot be confirmed but that have become conventional wisdom.

“They don’t want to lose him because he is a gold mine for solving crises, usually financial crises,” said Attia Essawy, an Egyptian writer with expertise in African affairs. “He is searching for a role; he wants to have a role regardless of where.”

While Libya’s strongman is enjoying his burnished image, it has come at a cost to his nation of 5.5 million people and to the approximately two million Africans who have flocked to Libya believing that they would find warm receptions, good jobs and, perhaps, an easy path to Europe. Instead, they found a hostile environment and a struggle just to eat.

“It is a burden,” Ali Abd Alaziz Isawi, who served for two years as the minister of economy, trade and investment, said of the army of illegal immigrants living in Libya. “They are a burden on health care, they spread disease, crime. They are illegal.”

All over this capital city, illegal African immigrants line up along roadways, across bridges and at traffic circles hoping to be selected for menial day jobs that pay about $8. They call the areas where they congregate “the hustling grounds,” which are always crowded with desperate faces from early morning until well past sundown.

Many people in Tripoli said they resented the presence of so many illegal workers. “We don’t like them,” said Moustafa Saleh, 28, who is unemployed, echoing a popular sentiment. “They smuggle themselves through the desert, and the way they deal with us is not good.”

For the African migrants themselves, life in Libya is often a dead end. “They call us animals and slaves,” said Paul Oknonghou, 28, a Nigerian who lives with about a dozen other Nigerians in a house under construction that lacks glass in the window frames, running water, a bathroom or a kitchen. He said he and his friends considered themselves lucky that they did not have to sleep on the streets.

Thomas Thtakore, 26, who is from Ghana, entered Libya illegally a year ago after a three-month journey across mountains and desert. “I have no help; I sleep under a bridge near the river,” He said. He said his younger brother died on the way. “If I stay here, I will die.”

Mr. Thtakore was about to be flown back to Ghana by the International Organization for Migration, a nongovernmental group that helps migrants return home. Since 2006, the group has helped about 3,000 travel home.

“If they find a job it can be good, but if they don’t, it can be a nightmare,” said Michele Bombassei, an official with the migration group, adding that most do not find jobs.

That hostile reality contrasts sharply with the image that Colonel Qaddafi likes to portray. His capital city is filled with billboards showing Libya as the one bright spot on the continent. In one billboard, Colonel Qaddafi appears as a savior as sun rays break over his shoulder and a crowd of black men and women reach toward him with outstretched arms.

His Africa agenda helps empower him in other ways, too.

Diplomats here said it gave him leverage in keeping African and European leaders listening and their doors open. If Libya sent all the migrants home, they would become a burden to poorer African nations, which would have to absorb them while losing out on the remittances they send home. At the same time, diplomats here said, Libya has made it plain to European countries, especially Italy, that if Libya chose to look the other way, most of those migrants would head for European shores.

“It’s a kind of soft power they use,” said one Western diplomat who works on Libyan affairs but requested anonymity for fear of antagonizing Libyan authorities.

Colonel Qaddafi will serve only a one-year term as chairman of the African Union, but his quest to use Africa as a stepping stone to greater world influence and credibility is likely to continue well past that. Last August, 200 kings and traditional African leaders traveled to Libya and anointed him with a more permanent moniker; they crowned him king of kings.