The leadership of Nippon Ishin no Kai (Japan Restoration Party) agreed Saturday to promote Osaka Mayor and deputy chief Toru Hashimoto to coleader to boost the party's media exposure ahead of the Upper House election.

Hashimoto's promotion will be formalized at a party convention in the near future. By allowing the outspoken mayor to jointly lead Nippon Ishin alongside current head Shintaro Ishihara, the party hopes to increase his media presence so he can better get its message out, especially before the House of Councilors poll this summer.

Formed last year by Hashimoto, Nippon Ishin merged in November with Ishihara's Taiyo no To (The Sunrise Party) to challenge the major national parties in the Dec. 16 general election.

The party won 54 seats in the 480-seat Lower House poll, making it the third-largest group after the ruling Liberal Democratic Party and the Democratic Party of Japan, which fell from power.