By one measure, next month¡¯s Upper House election is probably Japan¡¯s most important national poll ever.

The race, which kicked off Wednesday, could pave the way for Prime Minister Shinzo Abe to make history: to revise the U.S.-drafted Constitution nationalists see as a humiliating remnant of Japan¡¯s World War II defeat. Since its inception nearly 70 years?ago, the national charter has not been tweaked once.

Although Abe¡¯s ruling Liberal Democratic Party and its junior partner, Komeito, already hold a two-thirds majority in the 475-seat Lower House, they have yet to achieve this in the 242-seat Upper House. Abe wants to change this by winning big in the July 10 election, allowing pro-amendment forces to control two-thirds in both chambers ¡ª a scenario that would give him leverage to call a national referendum on constitutional revisions.