TOKYO - Japan's centrist opposition alliance stood on the brink of falling apart Monday, with sources saying members who joined from the Komeito party just months ago could leave the group.

The development follows the collapse of talks on the incorporation by the Centrist Reform Alliance of members of Komeito and the Constitutional Democratic Party of Japan in a three-way merger to counter the ruling coalition led by Prime Minister Sanae Takaichi.

The leaders of the three opposition parties are scheduled to meet later in the day to make a formal decision regarding the merger plan.

The Centrist Reform Alliance was formed in January. Following the February general election, it has 49 lawmakers, 28 from Komeito and 21 from the CDPJ, in the House of Representatives, the more powerful lower house controlled by the ruling Liberal Democratic Party and its coalition partner, the Japan Innovation Party.

Komeito and CDPJ lawmakers continue to sit separately in the House of Councillors, in which the ruling coalition does not hold a majority.

The focus will now shift to the opposition parties' future cooperation ahead of unified local elections next year, with political analysts saying the fragmentation of the opposition camp will benefit the ruling parties.

After months of talks, CDPJ leader Shunichi Mizuoka said in a meeting with his counterparts from the CRA and Komeito on Friday that his party will not join the alliance.

His call for exploring new forms of cooperation, such as forming a joint caucus in the upper house, was rejected by a senior Komeito executive.

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