Some members of Japan's Democratic Party for the People will not participate in a merger with a larger opposition party due to disagreements over policy, the former's leader said Tuesday.

Yuichiro Tamaki said he is among the lawmakers choosing to splinter off rather than join forces with the Constitutional Democratic Party of Japan, ending months of discussions aimed at building a united front against Prime Minister Shinzo Abe's ruling coalition.

"We were unable to agree on key policies such as lowering the consumption tax," Tamaki said at a news conference following a meeting of the DPP leadership.