Back in April when Prime Minister Shinzo Abe raised the consumption tax, he was betting he could break a jinx that has doomed leaders who took similar action to losing their jobs.

Now, wounded by Cabinet scandals and growing doubts about his radical "Abenomics" prescription to revive an economy scarred by years of deflation, Abe must decide whether to roll the dice again.

A shock move by the Bank of Japan on Friday to expand its massive asset-buying stimulus program — in the hope of stoking more inflation — could boost the chances of another rise in the unpopular levy from October, especially if followed by promises of additional fiscal stimulus to help offset the pain.