Prime Minister Shinzo Abe's support slid 10 points to 26 percent in a poll published Sunday, a day before he is to be grilled in the Diet over a suspected scandal that is cutting his ratings to the lowest since he took office in 2012.

The July 22-23 Mainichi newspaper poll also showed that 56 percent of respondents did not back his government, a 12 point rise from a previous survey in June.

The precipitous drop in support does not immediately threaten Abe's job, but clouds the prime minister's outlook. Abe was until recently seen as on track to become the nation's longest-serving prime minister by winning a third three-year term when his current tenure ends in September 2018.