The most prominent leader of Japan's beleaguered opposition is seeking to dent Prime Minister Shinzo Abe's popularity, blasting his failure to uplift women and his rush to change the pacifist Constitution.

"They should be ashamed to use the word 'womenomics,' " Democratic Party leader Renho, the 49-year-old mother of twins, said in an interview in Tokyo late Thursday when asked about the borrowed term Abe often uses to describe his efforts. "It's an embarrassment."

While Renho drew plaudits for becoming the first female leader of a major Japanese party in more than a decade last year, her approach has so far failed to resonate with voters. Abe remains on course to win an election due by the end of next year that could open the way for him to become the country's longest-serving prime minister.