The race to become Japan's sixth leader in five years was blown wide open on August 22 when former foreign minister Seiji Maehara, 49, decided to run.

That cut sharply into the chances of Finance Minister Yoshihiko Noda, a fiscal conservative. The support base for the two men overlaps in the Democratic Party of Japan (DPJ) -- and whoever is elected next week as leader of the party with control of the lower house will become prime minister.

Japan's new leader will have to grapple with a soaring yen that threatens exports, step up efforts to rebuild from the March earthquake and tsunami and end a radiation crisis at the Fukushima nuclear plant -- all while trying to curb public debt and cure the ills of a fast-aging society.

But concerns run deep as to whether the next prime minister will fare any better than his predecessors in the face of a divided parliament and ruling party split by policies and personal feuds.

Mr. Kan, whose voter support has sunk below 20 percent, pledged in June to step down after achieving certain tasks. With key bills expected to pass this week, the DPJ is set to pick a successor on August 29. One of those bills, to promote renewable energy sources such as solar power, was approved by a lower house panel on August 23.