TOKYO (Reuters) - Sixty percent of Japanese voters want Prime Minister Naoto Kan to resign by the end of August, a survey showed on Monday, the latest sign of mounting pressure on the unpopular leader to keep a pledge to quit as Japan struggles with reconstruction and a nuclear crisis.
A political stalemate over Kan's departure risks slowing efforts to recover from the March 11 earthquake and tsunami and the consequent radiation crisis at Tokyo Electric Power Co's Fukushima nuclear plant, and could delay steps to tackle structural problems including massive public debt.
Kan, under fire for his response to the March disaster, pledged this month to step down to quell a rebellion in his Democratic Party of Japan (DPJ), enabling him to survive a no-confidence vote, but has declined to say when he will go.
The survey by the Nikkei business daily showed 42 percent want Kan, Japan's fifth premier in as many years, to resign as soon as possible -- twice the figure in a May poll. Another 18 percent think he should quit by the end of August, when the current session of parliament concludes.
Kan has said he wants to stay on at least long enough to enact a bill enabling the government to issue bonds to fund about 40 percent of a $1 trillion budget for the year from April 1, a small extra budget to help with recovery from the tsunami, and measures to promote renewable energy sources.
Opposition parties, which control parliament's upper house and can block bills other than treaties and budgets, look set to help pass the small extra budget.
But they want changes to the ruling DPJ's spending plans in return for backing the bond issuance bill and are cautious about the renewable energy bill, which businesses fear will raise electricity costs.
Kan's critics in the ruling party, including some former backers, are also growing increasingly restive.
Six party executives including Chief Cabinet Secretary Yukio Edano and DPJ Secretary-General Katsuya Okada agreed in a meeting on Sunday that Kan should resign during the current parliament session, the Yomiuri newspaper reported.
But it was unclear how they intend to force Kan to do so if he wants to stay on.
The prime minister kept his opponents guessing on Monday when he asked Shizuka Kamei, the leader of junior coalition member the People's New Party, to become vice prime minister.
Kamei turned down Kan's request but agreed to become a "special aide" to the prime minister.
(Reporting by Linda Sieg, Yoko Kubota and Shinichi Saoshiro; Editing by Michael Watson)