An endeavor to merge the two largest opposition parties in Japan ground to a halt Tuesday, after the Democratic Party for the People failed to reach internal consensus ahead of a deadline on consolidation the previous day.

"We think it's regrettable, although we believe that the DPP ... did the best job it could. But at this point, we think we didn't reach an agreement between our very limit and their very limit," said Tetsuro Fukuyama, secretary-general of the Constitutional Democratic Party of Japan, on Tuesday afternoon after a meeting with DPP Secretary-General Hirofumi Hirano. He added that the two parties will continue to cooperate in the Diet.

The parties have been working for weeks on the proposed consolidation in a bid to establish a "formidable alternative" to the ruling bloc — the Liberal Democratic Party led by Prime Minister Shinzo Abe along with coalition partner Komeito — by the beginning of the Diet session, which was Monday. Fukuyama's comment signals that the merger proposal will be shelved, at least for now.