Prime Minister Taro Aso's ¥2 trillion cash handout program, his key stimulus plan, is under threat after former Prime Minister Junichiro Koizumi, arguably Japan's most popular lawmaker, openly dismissed its importance.

During a Liberal Democratic Party executive meeting on postal privatization Thursday, Koizumi not only expressed disdain over Aso's recent verbal gaffes and policy flip-flops, but went on to criticize the handout program.

"I don't think (the bills for the fiscal 2008 extra budget) should be passed" by holding a revote in the Lower House, Koizumi said Thursday, hinting he may openly oppose the Aso-backed bills.