Only the Japanese Communist Party can act as a counterweight to the ruling Liberal Democratic Party in the Upper House election, especially against Prime Minister Shinzo Abe's economic and constitutional revision plans, JCP Chairman Kazuo Shii declared Saturday.

In an interview with The Japan Times and other media organizations, Shii voiced confidence that the JCP will capitalize on the momentum generated in last Sunday's Tokyo Metropolitan Assembly election, where the party doubled its number of seats.

Shii said the JCP became the third-largest party in the assembly, after the LDP and its ruling coalition ally, New Komeito, because voters recognized it as a viable alternative.