The government and the ruling Liberal Democratic Party have agreed to convene an extraordinary Diet session on Sept. 26, a top LDP official says.
Speaking to reporters at LDP headquarters in Tokyo, Secretary-General Toshihiro Nikai said Tuesday that the party picked the date in consultation with the office of Prime Minister Shinzo Abe.
The LDP won big in the House of Councilors election in July after focusing on economic policies, but the most significant result of the poll was that it brought Abe's goal of amending the pacifist Constitution closer to reality by giving the pro-amendment forces the supermajority required to kick-start the process.
The session was timed to open after the Democratic Party's leadership election on Sept. 15.
According to a senior LDP member, Abe had suggested starting it on Sept. 13 or 16 to make time to introduce a bill to ratify the Trans-Pacific Partnership trade pact.
The ratification of the TPP, which Japan inked with 11 other nations in February, is a cornerstone of the Abe administration's sputtering growth strategy.
But Nikai and other LDP heavyweights pushed for a later start date to give the opposition camp's leadership enough time to prepare for the extraordinary session and keep the Diet running smoothly.
DP Deputy President Renho and former Foreign Minister Seiji Maehara are set to face off in the contest, with campaigning set to begin on Friday.
The opening date also reflects Abe's likely diplomatic schedule for this month, including a trip to attend the U.N. General Assembly in New York.
In addition to bill for ratifying the TPP, legislators will face a mounting list of contentious issues in the extra session, including a proposed second supplementary budget for fiscal 2016 ending in March.
Proposals in the administration suggest the session might conclude in either late November or early December.