Prime Minister Naoto Kan has begun to advocate raising the consumption tax to 10 percent, attacking the political hot potato head-on.

But experts aren't terribly impressed with Kan's tax pledge, saying a hike to 10 percent simply isn't enough to ward off a looming fiscal crisis.

The government probably won't be able to meet its goal of achieving a primary budget surplus by the end of fiscal 2020, either, they said, adding that the consumption tax would need to be raised to at least 15 percent to get the government on track for steady fiscal rehabilitation.