TOKYO, Aug 25 (Reuters) - Japanese Prime Minister Yoshihide Suga and ruling party heavyweight Toshihiro Nikai were set to meet on Wednesday to discuss the timing and the format of a party leadership vote, officials involved in the talks said. Nikai, an influential member of the ruling Liberal Democratic Party (LDP), has said he backs the re-appointment of Suga as party head, a position ensuring Suga would remain prime minister and lead the party in the looming general election. Japan"s largest newspaper the Yomiuri daily said on Wednesday that in addition to Nikai"s faction, the leadership of four other main groups in the LDP also favoured Suga for the top job, although younger, more vulnerable MPs opposed the unpopular premier. Suga took office last September after Shinzo Abe quit citing ill health, and his term expires at the end of next month. The premier"s ratings have fallen below 30% as Japan battles its worst wave of COVID-19 infections, and some in the party want to replace him before the general election. Suga has repeatedly said he would run in the leadership contest for another term, though a former foreign minister, Fumio Kishida, is likely to challenge him in the vote, which is expected to take place on Sept. 29. LDP members of parliament and grassroots party members are expected to be eligible to vote in the poll. There had been speculation that Suga may aim to first call a general election, win a majority of seats, then use the victory to help him win another term as party leader. But Kyodo news agency, citing unnamed sources, said late on Tuesday Suga was not planning to dissolve the lower house of parliament, a key step for calling a snap election, before the party leadership vote. Nikai has said Wednesday"s talks would be about "the future of the party and the country". Party officials said the talks were set to start at 11 a.m. (2:00 a.m. GMT) at the LDP"s headquarters in central Tokyo. Nikai played a major role in ensuring Suga"s victory in the previous LDP leadership race last year. Suga was scheduled to hold a news conference at 9 p.m. (12:00 p.m. GMT) on the expansion of the COVID-19 state of emergency to eight more prefectures, including the northern island of Hokkaido, as infections show no sign of slowing.