Prime Minister Naoto Kan's struggle to fund the nation's budget and avoid an early election suffered another setback when his foreign minister quit Sunday over illegal donations and a poll showed fewer than one voter in four supports him, and a stock slide heightened the sense of unease.

Foreign Minister Seiji Maehara, 48, resigned late Sunday after admitting he had received ¥250,000 ($3,038) since 2005 from a South Korean national in Japan he has known since childhood. The ruling Democratic Party of Japan was already hit by former leader Ichiro Ozawa's indictment on unrelated charges of violating political fund reporting laws, which also ban foreign contributions.

Kan has failed to persuade the opposition to authorize ¥44.3 trillion in government bonds to finance the budget and faces dissent in the DPJ over a push to raise the sales tax to cope with soaring debt costs. The stalemate has increased the possibility Kan will have to step down, becoming the fifth straight prime minister to last no more than a year.