An opposition party member will lead a powerful budget committee in Japan's lower house for the first time in three decades after the ruling camp agreed Thursday to leave its hold of the critical post that affects parliamentary deliberations, in a fresh setback for Prime Minister Shigeru Ishiba.

Giving the chair's post to the main opposition party, the Constitutional Democratic Party of Japan, means Ishiba's Liberal Democratic Party and its coalition partner, the Komeito party, will have to heed to opposition demands for the prime minister to attend a sufficient number of Diet deliberations.

The ruling coalition lost its majority control of the House of Representatives in the Oct 27 general election, while the opposition camp, particularly the CDPJ and the Democratic Party for the People, increased their seats.

Given the outcome, the number of ruling coalition members who chair parliamentary committees dealing with issues such as diplomacy, finance and national security will also decrease.

With the LDP and Komeito no longer controlling the powerful chamber, Ishiba could face some high hurdles in seeking parliamentary approval of budget plans and bills.

The government plans to draw up a supplementary budget for the current fiscal year to next March to fund additional inflation-relief measures and a full-year state budget for fiscal 2025 before year-end.

The last time Japan's lower house had an opposition member as chair of the Budget Committee was in 1994, under the minority government of Tsutomu Hata.

Ishiba, who became prime minister in October, is exploring policy coordination with the opposition. The ruling bloc can cross the majority line of 233 with the support of the DPP, which now has 28 seats.

The opposition initially did not agree on a government plan to hold a four-day special Diet session from Monday, which is necessary to reelect Ishiba as prime minister.

Ishiba is likely to secure enough support to be reelected as CDPJ leader Yoshihiko Noda is also set to fall short of a majority in the first round of voting, a requisite for a new leader to be chosen in parliament.

Yuichiro Tamaki, head of the DPP, has said its lawmakers will vote for him. If a runoff takes place, all votes cast for Tamaki would become invalid, favoring Ishiba.

Nobuyuki Baba, head of Japan's second-largest opposition party, has announced his intention not to run in its leadership race scheduled for early next month, following its defeat in the general election last month.

Calls had been growing for Baba, who became leader of the right-leaning Japan Innovation Party in 2022, to take responsibility for its decline from 43 seats to 38 in the election.

Baba's replacement as leader could affect the JIP's current stance of not cooperating with the ruling coalition led by Ishiba, analysts said.

The JIP has been trying to bolster its support base beyond the Kansai region centered on Osaka. In a social media post on Wednesday night, Baba said, "It is essential for the Japan Innovation Party to make a fresh start and renew its leadership."

The successor of Baba, who started his political career as a member of the LDP, is slated to be selected at an extraordinary party convention on Dec. 1, with campaigning for the leadership race beginning on Nov. 17.

Meanwhile, Komeito, the LDP's coalition partner, decided to recommend transport minister Tetsuo Saito as its new leader at a meeting of its central executive committee, following the defeat of incumbent Keiichi Ishii in the snap election.

Komeito, backed by the lay Buddhist organization Soka Gakkai, is expected to formally appoint Saito as chief at its extraordinary party convention on Saturday.