TOKYO - The government and the ruling Liberal Democratic Party are making arrangements to convene an extraordinary parliament session possibly on Oct. 15 to pick the successor to Prime Minister Shigeru Ishiba, a senior official said Wednesday. The Diet is likely to elect the new prime minister the same day, paving the way for the launch of a new Cabinet. The next Japanese leader is likely to be the winner of the ruling Liberal Democratic Party leadership race to be held Saturday. The LDP leadership race is taking place as Ishiba decided to step down as party leader to take responsibility following setbacks in national elections since becoming prime minister in October last year. Five LDP lawmakers are running in the contest, including farm minister Shinjiro Koizumi, former internal affairs minister Sanae Takaichi and Chief Cabinet Secretary Yoshimasa Hayashi.