The ruling Liberal Democratic Party's closely watched leadership race is set to be announced Monday, kicking off the 12-day official election campaign period ahead of the Oct. 4 voting by party lawmakers.

It will be the first LDP presidential election since the party and its coalition partner, Komeito, lost their combined majority in both chambers of the country's parliament.

The parties lost their control of the House of Representatives, the all-important lower chamber, in last October's general election, and of the House of Councilors, the upper chamber, in the election in July this year.

Major issues in the race to choose a new LDP president to succeed Shigeru Ishiba, the country's outgoing prime minister, will include measures against rising prices of goods and services.

Attention is also likely to be paid to how candidates will refer to cooperation with opposition parties, with eyes on whether the current coalition framework should be expanded.

Five Lower House lawmakers are expected to file their candidacies in the election — agriculture minister Shinjiro Koizumi, 44, Sanae Takaichi, 64 and Takayuki Kobayashi, 50, both former economic security ministers, Chief Cabinet Secretary Yoshimasa Hayashi, 64, and former LDP Secretary-General Toshimitsu Motegi, 69.

On Sunday, Koizumi visited the city of Funabashi, Chiba Prefecture, east of Tokyo, and held talks with fishery industry people.

On how to cooperate with opposition parties, Koizumi told reporters later in the city of Saitama that expanding the coalition, rather than seeking partial alliances on a policy-by-policy basis, will help stabilize politics.

Kobayashi visited Tokyo's Haneda Airport to inspect work of immigration officers. "I will work to reduce the number of foreigners who violate rules and engage in illegal acts to zero."

Takaichi, in a recording of an internet program, stressed her stance of inheriting the growth-oriented economic policies of former Prime Minister Shinzo Abe.

Hayashi visited former LDP President Sadakazu Tanigaki at his home in Tokyo. "I will fight the election with words from Mr. Tanigaki as encouragement," Hayashi told reporters.

Motegi visited a kodomo shokudo cafeteria offering meals mainly to children in need. "I have already presented my policies," he told reporters after the visit to the facility in Tokyo, adding, "I will give detailed explanations on my pledges."

In last year's LDP presidential election, Takaichi placed first in the first vote, followed by Ishiba. She lost to Ishiba in the runoff. In the first vote, Koizumi came third, Hayashi fourth, Kobayashi fifth and Motegi sixth.

On Monday, candidacies will be accepted from 10 a.m. Candidates will attend an event starting at 1 p.m. to present their policies and views on various issues.

Candidates will vie for a total of 590 votes — 295 from LDP lawmakers and as many from rank-and-file LDP members and supporters. The lawmakers — 195 Lower House members and 100 Upper House members — will cast their ballots on Oct. 4. Rank-and-file members and supporters will be asked to vote by mail.

If none of the candidates wins a majority vote, a runoff will be held between the top two contenders.