A political showdown is approaching as the two ruling parties continue talks to nail down details of tax reform by their self-imposed deadline of Jan. 24, in particular over whether daily essentials such as food should be exempt from the planned hike in the unpopular consumption tax.

New Komeito, the junior coalition partner of the Liberal Democratic Party, has insisted that lower rates should be applied to such items as meat, vegetables, rice and miso paste as well as newspapers to reduce the burden on low-income households.

The LDP, meanwhile, has agreed to eventually introduce special low rates for certain basic items but says it's impossible to launch such a radically new system in April 2014, when the tax is due to be raised to 8 percent from the current 5 percent.