President has to compete with his predecessor for humanitarian credit during his week-long visit

President Obama and the first family are on a lengthy trip to Africa, devoting an entire week to touting democratic developments and promoting free trade in Senegal, South Africa and Tanzania. But Obama is not the only president in the sub-Sahara this week.

It's Bush's third trip to Africa since leaving office, evidence of a continued commitment to providing live-saving drugs and other care to millions suffering from HIV

His predecessor, George W. Bush, is on his own humanitarian mission there, highlighting his legacy of combating AIDS in the region and putting Obama in the rare position of fighting Bush for the do-gooder limelight.

The White House has laid out a frenetic African itinerary for Obama, first lady Michelle Obama and daughters Sasha and Malia -- with the notable omission of Kenya, the birthplace of his father and home to many of his relatives. Kenya's new president is facing charges of crimes against humanity in the International Criminal Court -- not the kind of upbeat message Obama hopes to send back to the U.S.

Obama wants to promote economic ties between U.S. and Africa, warning that China and Russia are investing in the continent at a rapid clip.

With former South African President Nelson Mandela in critical condition, speculation is increasing over whether Obama will visit the ailing anti-apartheid leader or his family.

The trip's enormous price tag -- estimated between $60 million and $100 million -- has already overshadowed its lofty goals. The high costs largely stem from the phalanx of security accompanying the first family.

Revelations of U.S. spying programs and the international hunt for Edward Snowden also are drowning out the president's message and emboldening critics abroad. The Muslim Lawyers Association, a group based in Johannesburg, even called for Obama's arrest over lethal strikes by drones.

But it's a blast from the past that is likely the most awkward optic for Obama, and one he will be hard-pressed to avoid.

Obama is being forced to share the African stage with Bush, who made fighting AIDS there a top goal of his administration. It is the one Bush foreign-policy initiative lauded across party lines.

Hannah Abney, the communications director for the George. W. Bush Presidential Center, said the timing is purely coincidental.

It's Bush's third trip to Africa since leaving office, evidence of a continued commitment to providing live-saving drugs and other care to millions suffering from HIV.

He is visiting as part of a program to combat cervical cancer and will help refurbish a clinic in Zambia and then travel to Tanzania, where Laura Bush is organizing a forum for African first ladies, a project of the George W. Bush Institute.

U2 frontman and international philanthropist Bono has held up Bush's efforts to reduce AIDS in Africa as "the best advertisement for America there's ever gong to be."

"Even people who are snide and snarky about the United States of America have to admit that millions and millions of lives have been saved by American taxpayers," Bono said on Fox News in 2010.

With Bush bouncing around the country at the same time, it will be difficult for Obama to ignore the previous president's legacy of humanitarian projects in the region.

There are no plans for Obama and Bush to meet up, even though the two will overlap on July 2 in Tanzania, the last stop on the current president's schedule. Michelle Obama will attend the forum with Laura Bush to help promote women's health, education and economic independence.

Even before Obama left Washington for Senegal, the White House was on the defensive and appeared a tad testy when asked about the Bush AIDS legacy.

Ben Rhodes, deputy White House national security adviser, said the president has continued sending millions of dollars to Africa to fight HIV. Thanks to the work "under two administrations ... we have within reach an AIDS-free generation," Rhodes said.

Rhodes then abruptly shifted back to trip's talking points, stressing that "as a general matter" Africa doesn't need "handouts."

"Africa needs economic growth," he said. "And this notion that the only way to make an impact is to announce a high-dollar assistance program doesn't fit with the times as it relates to what Africans are looking for."