The Democratic Party of Japan and the smaller Liberal Party formally signed a merger deal Wednesday after managing to agree on candidates for the next House of Representatives general election.
The merger, which will see the absorption of the Liberal Party by the DPJ, creates an opposition party large enough to pose a challenge to the ruling Liberal Democratic Party.
The two parties put off filing the agreement with the Public Management, Home Affairs, Posts and Telecommunications Ministry until Friday after the negotiations lasted into the 11th hour.
Commenting on the merger, Prime Minister Junichiro Koizumi said the expanded DPJ is "not a force to be taken lightly."
At the same time, however, he showed confidence that his LDP can win the upcoming general election, saying: "The next election will one in which the people choose whether they want Koizumi or (DPJ head Naoto) Kan as prime minister. . . . I believe people will support the LDP if they judge that it has become a party for reform."
The DPJ and the Liberal Party have a combined 136 members in the 480-member House of Representatives and 66 seats in the 247-member House of Councilors. The LDP has 244 and 113 members, respectively.