South Korean authorities on Saturday started the official registration for candidates contesting in the May 9 presidential election. After a two-day registration, campaigning for the vote will kick off on Monday.

Twenty-six potential candidates had signed up with the National Election Commission in preliminary registrations on April 3, after former President Park Geun-hye was officially removed from office, prompting the rare presidential by-election. As of Friday, 21 candidates remained on the preliminary list after the rest withdrew. 

Presidential hopefuls seen as frontrunners in the election are Moon Jae-in of the liberal Democratic Party of Korea and Ahn Cheol-soo of the center-left People's Party.