TOKYO — The race to become Japan's next prime minister has set up an unpredictable leadership election — with candidates facing challenges over the pandemic, a stagnant economy and a region increasingly dominated by China.

The four-way contest for party president, set for Wednesday, is also the first election with two female candidates in a country where women are vastly underrepresented in politics.

The election is an internal fight within the Liberal Democratic Party, triggered by Japanese Prime Minister Yoshihide Suga’s decision to step down after just one year in power amid plummeting popularity over his handling of the coronavirus response, including a slow rollout of vaccines.

Because the party controls a majority in parliament, its new leader is likely to win the general election for prime minister in November.

The hurdles facing the new prime minister go beyond the pandemic, said Naoko Taniguchi, a political affairs researcher at Keio University.

“In addition, in a mid- to long-term perspective, they will also need to conquer international affairs — rise of China, change in U.S. global strategies, and the change in international order as a result — balance of finance and welfare, and the problems arising with the declining population,” Taniguchi said.

The party leadership election is typically an insular process negotiated through backroom deals among party elders. But the unpredictability of this race has injected energy and an unusual level of influence among the rank-and-file members, who may have a greater say this time.

Lully Miura, founder of the Yamaneko Research Institute, said the party election will serve to energize the base ahead of the general election.

“This time, the LDP presidential election will be very influenced by public opinion and the position of local party members, given the general election is very near,” she said.

Here are the candidates:

Taro Kono, 58

Kono, Japan’s social media-savvy vaccine chief, is reportedly backed by Suga, according to Japanese media.

Previously, he was foreign and defense minister. As minister of administrative and regulatory reform, he backed policies that challenged Japan’s bureaucratic machine, such as ending the use of fax machines in government business. In a country where octogenarians rule the political elite class, Kono is considered a younger, upstart candidate and somewhat of a social media whiz.

The popularity of Japan’s vaccine program may work in his favor, experts say. After a slow start, the program picked up quickly, and Japan has immunized citizens at a rapid clip.

Fumio Kishida, 64

Kishida, also a former foreign affairs minister, has had a lower public profile than Kono, but is well regarded among party leadership. Days before the election, Kono and Kishida appeared to be in the lead, according to polls.

When Kishida announced his candidacy — the first one out of the gate — he sought to draw a contrast between himself and Suga by emphasizing transparency and criticizing the administration’s handling of the pandemic as insufficient and slow.

Among Kishida’s banner platforms is decreasing the income gap, through redistributing wealth and reining in the market-oriented policies that have been the core part of the economic agenda of Suga’s predecessor, Shinzo Abe.

Sanae Takaichi, 60

Takaichi, who has served as internal affairs and communications minister, is a hawkish, Abe-backed candidate and an underdog.

She has pledged to continue Abe’s pro-growth economic policies and strongly opposes apologies for Japan’s wartime past. She has fought against allowing married couples to have different last names, and against allowing members of the imperial family’s maternal line to ascend the throne.

Among her most controversial views is that she will continue to visit the Yasukuni shrine, which is seen by some as a symbol of Japan’s past militarism and is likely to strain relations with China and South Korea.

Seiko Noda, 61

Noda, an 11th-hour entry, has served as minister of internal affairs and communications and as minister in charge of women’s empowerment.

She is considered a long shot, but her entry marked the first time in the party’s history with multiple female candidates in contention and drew attention to the lack of representation of women in elected office in Japan.

Noda is one of the most prominent female politicians in Japan and is known for her work on women’s issues, particularly after she became a mother at the age of 50 through in vitro fertilization.

She supports allowing married people having different last names. Her platform emphasizes diversity and gender equality, and supporting children and families to increase Japan’s plummeting birthrate.

Julia Mio Inuma contributed to this report.