Lee Jae-myung and Kim Moon-soo represent the opposite sides of a country polarized over former President Yoon Suk Yeol’s use of martial law and his ouster.

SEOUL (Reuters) - South Korea's conservatives dropped their presidential candidate on Saturday and reopened a process to pick a new nominee as the country's former prime minister joined the party to challenge a liberal frontrunner less than four weeks before the election.

Lee Jae-myung has been the front-runner in South Korea's presidential election, but his candidacy has been complicated by criminal trials he has decried as politically motivated.