Osaka Mayor and Nippon Ishin no Kai (Japan Restoration Party) head Toru Hashimoto indicated Friday evening that a merger with former Tokyo Gov. Shintaro Ishihara’s Taiyo no To (The Sunrise Party) is almost a done deal.

Hashimoto also said it is his understanding that Genzei Nippon (Tax Reduction Japan), a minor party headed by Nagoya Mayor Takashi Kawamura, will not join the merger of the two parties. Earlier Ishihara and Kawamura had announced plans to merge their parties.

“(I) have reached an agreement with party coleader Ishihara,” Hashimoto said after meeting with Ishihara at a Tokyo hotel.

However, Hashimoto did not provide any more details of how Nippon Ishin no Kai and Taiyo no To might cooperate on policies. He and Ishihara have fundamental differences in areas ranging from the consumption tax to nuclear power to constitutional reforms.

Ishihara and other party executives are expected to try to form an internal consensus on the issues before Saturday’s Ishihara-Hashimoto meeting in Osaka.

To merge, the two parties would need to overcome a number of differences, in particular whether to support Japan’s participation in the Trans-Pacific Partnership free-trade talks and Hashimoto’s call for the eventual abolition of all nuclear power stations in Japan.

The Hashimoto-Ishihara party merger, if realized, is likely to attract a considerable number of swing voters who now do not support any existing parties, in particular the Democratic Party of Japan or the Liberal Democratic Party, the nation’s two largest political forces.

Earlier Friday, Taiyo no To key member Hiroyuki Sonoda told reporters in Tokyo that his party and Nippon Ishin no Kai at first will try to coordinate policies to merge, and Genzei Nippon may later consider whether to accept those terms and join the two.

Nippon Ishin no Kai has advocated participating in the TPP talks, as well as abolishing all nuclear plants by 2030. Whether Taiyo no To can accept these goals will be key in the merger talks.