DAR ES SALAAM, Tanzania  President Bush has been smothered with affection here, never more so than on Sunday, when he sat at a wooden desk under a sweltering sun with President Jakaya Kikwete by his side and signed a $698 million grant of foreign aid to Tanzania.

But while people here in the capital city of this East African nation are excited about Mr. Bush, another American politician seems to excite them even more  Senator Barack Obama.

Mr. Bush is on a six-day, five-country tour to spotlight American efforts to fight poverty and disease in Africa. Though the president’s face is on billboards all over town, the name Obama is on the lips of Tanzanians  from taxi drivers to city merchants to the artisans who sell wooden Masai warriors in makeshift stalls at a dusty open-air market on the outskirts of town.

Halfway around the world, Mr. Bush cannot escape the race to succeed him.

“It seemed like there was a lot of excitement for me  wait a minute, maybe you missed it!” he said, only half in jest, on Sunday, after Mr. Kikwete was asked about Mr. Obama during their joint news conference here.