While Donald Trump is set to inject a dose of fiscal medicine into the world's biggest economy, any move by Shinzo Abe to further strengthen Japan's fiscal stimulus program faces the challenge of disappointing tax receipts and a record debt burden.

The government already plans to spend ¥100 trillion this fiscal year in its main budget and two extra spending packages. That's close to the all-time high in outlays during the global financial crisis.

A third supplementary budget is on the drawing board to reconcile current-year spending and revenue figures, according to government sources. As to whether it goes beyond being a clerical package and takes on stimulus measures, that's a function of what happens with politics, they said.