Japan's Prime Minister Naoto Kan, weighed by low support ratings, is now "on the edge of a cliff" after his high-profile foreign minister quit over a funding scandal, newspapers say.
"The Kan government faces its biggest crisis" since Kan took power in June last year, the liberal newspaper Mainichi Shimbun said in an editorial.
"They are in a crisis situation of whether the Kan government, or even the rule of the Democratic Party of Japan (DPJ), will collapse," it said a day after Seiji Maehara stepped down.
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Maehara, 48, announced his resignation at a hastily arranged press conference late on Sunday after he admitted he received around Y250,000 yen ($3,000) over recent years from an ethnic Korean who is not a citizen.
He had been seen as a likely successor to Kan, who has struggled in the face of support ratings below 20 per cent and a split parliament that has threatened to derail his reform agenda.
Under Japanese law, it is illegal for politicians to accept donations from a foreign national and the scandal has been all the more damaging to Maehara, who as foreign minister had taken a hawkish and strongly patriotic stance.
The Nikkei business daily said "the Kan government is standing on the edge of a cliff after the foreign minister's resignation".
The conservative Yomiuri said "Prime Minister Kan has been driven into a tight corner" while the liberal Asahi said "the prime minister's political ground is bound to weaken further".
The DPJ swept to power in 2009 ending more than half a century of almost unbroken conservative rule.
Speaking in parliament on Monday, Kan said he had tried to persuade Maehara to stay on but said the former foreign minister was determined to go.
National broadcaster NHK said Chief Cabinet Secretary Yukio Edano would double as foreign minister for the time being.
The ambitious Maehara came under pressure last week when he admitted he had accepted the donations.
The Yomiuri argued that "not a small number of people may have given up on Mr Kan's qualifications and ability as prime minister" after a series of scandals involving cabinet ministers and stalled parliament.
