Nagoya Mayor Takashi Kawamura said Thursday he has struck a basic agreement to merge his group with a new party led by veteran lawmaker Shizuka Kamei ahead of next month's election.

The agreement for Kawamura's political group, Genzei Nippon (Tax Reduction Japan), to tie up with Kamei's party, which is highly critical of Prime Minister Yoshihiko Noda's key policies, came as a raft of small parties are trying to form a "third force" to take on the major ruling and opposition parties in the Dec. 16 election.

Kawamura told reporters his party shares many similar policies with Kamei's group, including their objections to participating in the Trans-Pacific Partnership free-trade talks and the consumption tax hike.

The two parties were scheduled to hold a news conference later Thursday. By merging, they will be able to meet the requirements to be regarded as a national political party, which needs at least five Diet lawmakers.

Kamei, who left ruling coalition member Kokumin Shinto (People's New Party) in April to protest the consumption tax hike, announced the formation of his new party Monday, along with former farm minister and DPJ defector Masahiko Yamada.

The agreement came a day after Kawamura's party gave up on merging with Nippon Ishin no Kai (Japan Restoration Party), which was formed by Osaka Mayor Toru Hashimoto and is now led by former Tokyo Gov. Shintaro Ishihara.

On Wednesday, Genzei Nippon saw Koki Kobayashi resign as a party member. Kobayashi, who left the DPJ in August before signing up with Kawamura's party, has expressed his intention to join Nippon Ishin.

Kawamura and Kamei are reportedly interested in joining hands with Ichiro Ozawa's Kokumin no Seikatsu ga Daiichi (People's Life First), but Kawamura said early Thursday that no such discussions have been held.