Abe was until recently seen as being on track to become Japan's longest-serving prime minister by winning a third three-year term when his current tenure ends in September 2018.
Further pressure is likely to come from Sunday's victory by an opposition candidate in the mayoral election for the northern city of Sendai. Abe's party suffered a devastating defeat in
elections for the Tokyo assembly earlier this month.
A July 22-23 Mainichi newspaper poll published on Sunday showed Abe's support slipping 10 points to 26 percent from the previous survey in June. It also showed that 56 percent of respondents did not back Abe's government, a 12 point rise.
Abe and his aides have repeatedly denied intervening to help Kake Gakuen (Kake Educational Institution) win approval for a veterinary school in a special economic zone. Its director, Kotaro Kake, is a friend of Abe.
Abe will appear at an ad hoc committee meeting in parliament on Monday. Also appearing at the session will be his aide, Hiroto Izumi, and Kihei Maekawa, who resigned as the education ministry's top bureaucrat in January and has accused the government of distorting the approval process.
The scandals, and a perception among many voters that Abe's administration is taking them for granted, are encouraging rivals and casting doubt on Abe's hopes for a third term as ruling Liberal Democratic Party leader.
Abe is expected to reshuffle his cabinet early next month in an effort to repair his damaged ratings, a step often taken by beleaguered leaders but one that can backfire if novice ministers become embroiled in scandals or make gaffes.
Also in trouble is Defence Minister Tomomi Inada, an Abe protege, who faces calls to resign over media reports of direct involvement in a ministry cover-up of documents about a sensitive peacekeeping operation. She denies the reports Opposition lawmakers are also expected to grill Abe about media reports that Inada allowed defence officials to conceal logs about the activities of the Self-Defense Forces, as Japan's military is known, in a U.N.-led peacekeeping operation in South Sudan.