Ahn Cheol-soo, leader of the minor opposition People's Party, will declare his third presidential run this week, the party said Sunday, shaping next March's election as a four-way race.

Ahn will hold a ceremony at the National Assembly on Monday to declare his bid, the party said.

It will be the third time for the former medical doctor and software entrepreneur to run for president.

In November 2012, Ahn withdrew from the race less than a month before the election, giving his support for Moon Jae-in, then-candidate of the main opposition party. He ran again in the 2017 election and finished third with 21.41 percent of vote.

Ahn will compete against former Gyeonggi Gov. Lee Jae-myung, presidential nominee of the ruling Democratic Party, a candidate from the main opposition People Power Party (PPP) and Rep. Sim Sang-jeung of the progressive minor opposition Justice Party.

PPP's nominee will likely be either former prosecutor-general Yoon Seok-youl or Rep. Hong Joon-pyo. The party is scheduled to elect its nominee on Friday. (Yonhap)