TOKYO, Sept 29 (Reuters) - Japan's ruling party votes for a new leader on Wednesday who will almost certainly become the next prime minister ahead of a general election due in weeks and with the economy staggering from the COVID-19 pandemic.

Running for the top post are popular vaccine minister Taro Kono, 58, a U.S.-educated former defence and foreign minister seen as a maverick; ex-foreign minister Fumio Kishida, 64, a consensus-builder saddled with a bland image; former internal affairs minister Sanae Takaichi, 60, an ultra-conservative; and Seiko Noda, 61, from the party's dwindling liberal wing.

Party lawmakers will begin voting at 1:00 p.m. Japan time (0400 GMT) at a Tokyo hotel. Results from ballots of rank-and-file members and lawmakers are scheduled to be announced at 2:20 p.m.

If any candidate gets a clear majority, though projections show it is unlikely, that person will become the winner.

If not, the top two candidates in the first round will immediately go into a run-off vote. The results of the second round of voting are expected around 3:40 p.m.

Prime Minister Yoshihide Suga, his support in tatters ahead of the election, in a surprise move said he would step down after only a year as the Liberal Democratic Party (LDP) leader at a scheduled Sept. 29 party vote.

The new party chief is expected to become the next prime minister as the LDP holds a majority in the parliament's powerful lower house, but the contest has created political uncertainty in Japan with four candidates.

Last year, LDP factions rallied around Suga after Prime Minister Shinzo Abe quit following his nearly eight-year tenure, citing ill-health. But Suga's ratings tanked over his handling of the pandemic, prompting him to announce his departure ahead of a general election that must be held by Nov. 28.