Photo/Illutration Former Prime Minister Yoshihiko Noda speaks to reporters in Nasu-Shiobara, Tochigi Prefecture, on Aug. 24. (Nozomi Matsui)

Yoshihiko Noda, a former prime minister, plans to run in the leadership contest of the main opposition Constitutional Democratic Party of Japan to be held next month, sources said.

Noda, 67, who currently serves as one of the party’s chief executive advisers, is expected to announce his candidacy as early as this week, the sources said.

The CDP’s leadership election is scheduled for Sept. 23. Official campaigning will start on Sept. 7.

Noda plans to call for a change in government by defeating the ruling Liberal Democratic Party in the next Lower House election, the sources said.

He is also expected to call the LDP to account over a recent fund-raising scandal and seek thorough political reform, they said.

In a speech in Nasu-Shiobara, Tochigi Prefecture, on Aug. 24, Noda criticized LDP lawmakers for preparing for their own leadership contest on Sept. 27 without earnestly reflecting on the scandal.

“The CDP will be required to root out the questions surrounding money in politics,” he said.

Noda served as prime minister between 2011 and 2012 as leader of the now-defunct Democratic Party of Japan.

The party ended its three years in power when it was defeated by the LDP in a Lower House election in December 2012 that was called by Noda.

Yukio Edano, 60, former party leader, has announced his candidacy for the CDP leadership contest, while Kenta Izumi, 50, the incumbent leader, is trying to secure endorsements from 20 party lawmakers to seek re-election.