The main ruling and opposition parties agreed Thursday to pick the successor to Prime Minister Junichiro Koizumi in an extra Diet session on Sept. 26, lawmakers said.

The Diet is expected to tap Chief Cabinet Secretary Shinzo Abe as the new prime minister, since he is widely expected to be elected president of the Liberal Democratic Party on Sept. 20.

Hiroyuki Hosoda, the LDP's Diet affairs committee chairman, and Kozo Watanabe, his counterpart from the Democratic Party of Japan, the main opposition party, agreed on the schedule Thursday morning in the Diet, the lawmakers said.

According to the agreement, on the day the extra session convenes, both chambers will hold separate elections in the afternoon to select the next prime minister.

The Lower House's pick will prevail if the results between the two chambers differ.

Abe earlier vowed that he would try to get the Diet to enact bills in the session to revise Japan's postwar basic education law and to upgrade the Defense Agency into a ministry.