DES MOINES (AP) - Former Iowa Gov. Tom Vilsack and his wife, Christie, will accompany former President Clinton on a weeklong trip later this month through Africa.

They will cap the trip with a stop in Mexico City for an international conference on AIDS in early August.

In an interview Tuesday with The Associated Press, Vilsack said the invitation to take the trip grew out of the early endorsement he and his wife gave to Democratic presidential candidate Hillary Rodham Clinton. Vilsack endorsed Clinton soon after he dropped his bid for the nomination.

Vilsack campaigned extensively for Clinton, often accompanied by her husband.

"As a result of the campaign we traveled quite a bit with President Clinton and we developed a friendship," said Vilsack. "The president enjoys our company and we certainly enjoy his."

Despite his support, Hillary Rodham Clinton finished third in Iowa's leadoff precinct caucuses last January.

Vilsack said one goal of the trip was to gather information to aid Iowa State University in its efforts to improve food production in Africa. The former governor advises the college on that effort.

"This will give me a chance to meet with leaders and make sure they know what's going on at Iowa State," Vilsack said. "My hope is that I can come back with information that would allow me to better counsel and advise the university on its efforts. Hopefully, we'll be able to expand the reach of Iowa State."

Vilsack said the effort is part of a long-term project to modernize food production throughout Africa, where many crude production techniques are still used.

"Iowa State has developed a very extensive, comprehensive approach to this," Vilsack said. "It is a very rudimentary system in Africa."

Upgrading farming procedures could allow countries in Africa to take advantage of modern breakthroughs, such as genetically enhanced seeds that could dramatically increase food production, Vilsack said.

Clinton and the Vilsacks will travel to Ethiopia, Rwanda, Senegal and Liberia on the trip beginning July 28.

"It's a whirlwind tour and we'll be meeting with heads of state in some of those countries," Vilsack said.

The former president heads a foundation that does extensive work throughout Africa. He's well known in Africa and makes annual trips there on behalf of his foundation.

The trip will be Vilsack's second to Africa. He previously accompanied former United Nations Ambassador Andrew Young.