By Linda Sieg
TOKYO (Reuters) - Japanese Prime Minister Shinzo Abe, plagued by suspected cronyism scandals and cover-ups and with his ratings sliding, will likely step down in June, former leader Junichiro Koizumi was quoted on Monday as telling a weekly magazine.
A survey by broadcaster Nippon TV released on Sunday showed Abe's support had sunk to 26.7 percent, the lowest since the conservative lawmaker took office in December 2012. An Asahi newspaper poll published on Monday put his rating at 31 percent.
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Abe’s sliding ratings raise doubts over whether he can win a third three-year term as ruling Liberal Democratic Party (LDP) leader in a September vote, that he needs to win to stay in office, or whether he might even resign before the party vote.
Speculation has also emerged that Abe could call a snap general election as he did last October, when his ratings were in a similar slump.
The prime minister has repeatedly denied any wrongdoing.
The latest signs of trouble for Abe come ahead of his summit this week with U.S. President Donald Trump, where the difficult topics of North Korea's nuclear and missile threats and touchy trade matters will be on the agenda.
"The situation is getting dangerous. Won't Mr. Abe resign around the time parliament's session ends (on June 20)?" weekly magazine Aera's online site quoted Koizumi as saying in an interview.
Koizumi - a critic of Abe's support for nuclear power after the 2011 Fukushima crisis - said that if Abe hangs on, it could hurt LDP candidates in an upper house election next summer.
Crowds of protesters demonstrated near parliament on Saturday, holding signs saying "Abe is Over" and chanting "Abe quit!" Organizers said 50,000 had participated by the time the demonstration ended.
Abe last week denied again that he had intervened to ensure preferential treatment for educational institution Kake Gakuen, run by his friend Kotaro Kake, to set up a veterinary school.
He has also repeatedly denied that he or his wife intervened in a heavily discounted sale of state-owned land to another school operator, Moritomo Gakuen, with ties to his wife.
But the Asahi survey, in line with others, showed that two-thirds of voters don't trust Abe's explanations.
In another headache for Abe, the finance ministry's top bureaucrat is under fire after another weekly magazine reported that he had sexually harassed several female journalists.
Administrative Vice Finance Minister Junichi Fukuda told reporters he would issue a comment later on Monday after the daily Sankei newspaper reported that Abe had decided he would have to fired the bureaucrat.
Former cabinet minister Shigeru Ishiba, who has made clear he wants to challenge Abe for the top post, topped the list of politicians that respondents to a weekend Kyodo news agency survey saw as best suited to become the next premier, with 26.6 percent.
Popular young LDP lawmaker Shinjiro Koizumi - ex-prime minister Koizumi's son - ranked second with 25.2 percent, with Abe in third place with 18.3 percent. Former foreign minister Fumio Kishida, another possible contender, was fourth with 5.9 percent followed by Internal Affairs Minister Seiko Noda at 3.6 percent and Foreign Minister Taro Kono with 2.9 percent.
Among LDP supporters, however, Abe was top with 36.7 percent against 24.7 percent for Ishiba, Kyodo said.
(Reporting by Linda Sieg; Editing by Michael Perry)