Prime Minister Shinzo Abe announced Monday that he will dissolve the Lower House for a snap election when the Diet convenes for an extraordinary session Thursday, in a high-stakes political gamble that observers say could determine whether he survives as Japan's leader.

At a news conference Monday evening, Abe sought to justify the expected election on Oct. 22— widely criticized as an attempt at self-preservation — as an opportunity to seek a public mandate on his decision to divert revenue from the planned 2019 consumption tax hike to education and social security, despite the nation's snowballing public debt.

With Japan in the grip of a rapid demographic shrinkage, "we will go ahead with significant investment in order to solve major issues facing the working population in areas such as child-rearing and nursing care," Abe told the news conference in Tokyo.