Japan's parliament will convene an extraordinary session on Oct. 20, the head of the junior partner in the ruling coalition said Friday, the first parliamentary debate for Prime Minister Fumio Kishida's new Cabinet since its reshuffle earlier this month.

The main focus of the session is whether a draft supplementary budget will be submitted to parliament to fund a new economic package the premier recently outlined without dissolving the House of Representatives for a snap election.

Prime Minister Fumio Kishida arrives at his office in Tokyo on Sept. 29, 2023. (Kyodo) 

Speaking to reporters, Kishida said his government would submit a draft supplementary budget to the session, adding the ruling camp will focus its efforts on implementing stimulus steps and addressing other challenges.

Asked about the possibility of a Diet dissolution, Kishida said, "I am not thinking about anything other than the economic measures and responses to other challenges, which cannot be put off."

Kishida's decision to submit an extra budget to parliament reduces the likelihood that he will dissolve the lower house at the start of the upcoming session.

Komeito party chief Natsuo Yamaguchi told reporters that Kishida informed him of the plan for an extra Diet session earlier in the day. Kishida also relayed the schedule to some senior lawmakers of his Liberal Democratic Party, lawmakers said.

There has been speculation among lawmakers that he could dissolve the chamber at the session's start or once the ruling coalition finalizes details of the stimulus package, aimed at mitigating the pain of surging prices and supporting the economy, with deliberations on the supplementary budget left to a later Diet session.

Some lawmakers still speculate that Kishida will dissolve the lower house this year.

Kishida has vowed to swiftly start compiling a draft supplementary budget for the fiscal year through March 2024 after putting together stimulus measures by the end of October.

But the prime minister had previously remained mum on when he would submit the spending plan to the Diet, stoking speculation that he would postpone deliberations and dissolve the lower chamber.

Yamaguchi said he and Kishida did not talk about the draft budget during their meeting at the prime minister's office.

The next lower house election is not required to be called until 2025, when the four-year term of current members expire.

Struggling with low approval rates for his Cabinet, Kishida reshuffled his Cabinet and LDP executive lineup on Sept. 13. But the move has not led to significant improvement in support rates.

Kishida is likely to deliver a policy speech on the opening day of the extraordinary session, with questioning by other party leaders in both chambers taking place between Oct. 23 and 25, lawmakers say.

During the upcoming Diet debates, opposition lawmakers are likely to grill some of the new ministers over allegations of improper handling of political funds.

They are also likely to take up the release of treated radioactive water from the crippled Fukushima nuclear power plant into the sea since late August, which prompted China to impose a blanket ban on Japanese seafood imports.

Also on Friday, House of Representatives Speaker Hiroyuki Hosoda told people close to him that he has decided to resign after undergoing treatment for various health issues in recent months, sources close to the matter said.