Japan's governing party on Saturday elected former Economic Security Minister Sanae Takaichi as its new leader, making her likely to become the country's first female prime minister.

Takaichi beat Agriculture Minister Shinjiro Koizumi, the son of popular former Prime Minister Junichiro Koizumi, in a runoff in an intraparty vote by the Liberal Democratic Party.

The winner of the Liberal Democratic Party's intraparty vote is likely to be Japan's next prime minister because the party remains by far the largest in the lower house, which determines the national leader, and because opposition groups are highly splintered.

In the first round of voting, former Economic Security Minister Sanae Takaichi finished first with 183 votes and Agriculture Minister Shinjiro Koizumi placed second with 164 votes.

Because neither candidate reached a majority in the first round, the winner will be determined in an immediate two-way runoff, in a process that also involves decisions by party kingmakers such as former prime ministers Taro Aso and Fumio Kishida.

The LDP, whose consecutive losses in parliamentary elections in the past year have left it in the minority in both houses, wants to select a leader who can quickly address challenges in and outside Japan, while seeking cooperation from key opposition groups to implement its policies.

Five candidates -- two currently serving and three former ministers -- were vying for the LDP presidency.

Saturday's vote only involves 295 LDP parliamentarians and about 1 million dues-paying members. It only reflects 1% of the Japanese public.

Voting for the parliamentarians began Saturday afternoon at the LDP headquarters in Tokyo, where ballots sent from members around the country were also being counted.

Earlier polls had suggested the front-runners would be Koizumi, Takaichi and Chief Cabinet Secretary Yoshimasa Hayashi, a moderate veteran politician. Two others, Trade Minister Toshimitsu Motegi and Economic Minister Takayuki Kobayashi, were seen as less likely contenders.

Takaichi, a hardline ultra-conservative, would potentially be Japan's first female prime minister while Koizumi would be the youngest prime minister in more than a century.

The top contenders rallied with their supporters ahead of the vote, expressing confidence they would win.

A parliamentary vote is expected in mid-October. The LDP, which has been criticized by opposition leaders for creating a prolonged political vacuum, also needs to hurry because the winner will soon face a big diplomatic test: a possible summit with U.S. President Donald Trump , who could demand that Japan increase its defense spending.

A meeting is reportedly being planned for late October. Trump will travel to the Asia-Pacific Economic Cooperation summit in South Korea starting Oct. 31.

The LDP also needs help from the opposition, which it has long neglected. The party will likely look to expand its current coalition with the moderate centrist Komeito with at least one of the key opposition parties, which are more centrist.

All five candidates have called themselves "moderate conservatives" to show their willingness to work with the opposition.

They all campaigned for measures to combat rising prices and achieve larger salary increases, to strengthen defense and the economy, and for tougher measures on foreign workers. They stayed away from divisive liberal social issues such as gender equality and sexual diversity.

Experts say they avoided discussing their usual political views on historical issues, same-sex marriage and other contentious topics, including the party's political funds scandal, which was the biggest reason for their election losses, and anti-corruption measures. Their avoidance of these subjects raised doubts over the party's ability to regain public trust, analysts said.

Japan's ruling party elects Sanae Takaichi as new leader, likely to become 1st female PM