South Korea's election authorities began taking official registrations Saturday from those seeking to become the country's chief executive in the upcoming election, as two front-runners submitted their paperwork.

After the two-day registration, the official campaign period for the May 9 presidential election will begin Monday, according to the National Election Commission.

A total of 26 potential candidates had registered with the NEC after preliminary registrations began on March 10, when former President Park Geun-hye was forced out of office by a Constitutional Court ruling, prompting the rare presidential by-election.

As of Friday, 21 remained on the list after the rest withdrew their preliminary, mostly self-imposed candidacies, according to the NEC.

How many will still run after the registration period remained to be seen, but a number of preliminary candidates are expected to drop out as the official registration will cost each 300 million won ($264,500) in trust funds, while the pre-registration cost nothing.

The money is refundable only if the candidate wins more than 15 percent of all eligible votes cast, according to the NEC.

Currently, only two presidential hopefuls are seen able to garner as much support. They are Moon Jae-in of the liberal Democratic Party of Korea and Ahn Cheol-soo of the center-left People's Party.

Both enjoyed an approval rating of over 30 percent each in most recent polls on the upcoming election.

In a statement, Moon said "a new history has begun" in South Korea.

"The new Korea is a country for everyone," he said. "It's time for us to bring our hearts together. And to build a new Korea, I will embrace everyone."

Ahn, who has been making grounds on Moon of late, said he will try to "win the election for the people."

"At this presidential election, we'll be voting for the future of the country," he said. "We can choose to return to the past, or to open up a new future."

The election is expected to involve at least three others from the same number of political parties that currently hold parliamentary seats.

Hong Joon-pyo of the former ruling Liberty Korea Party, who currently maintains a distant third with an approval rating of less than 10 percent, officially joined Moon and Ahn in the race Saturday, while Rep. Yoo Seong-min of the splinter conservative Bareun Party and Rep. Sim Sang-jeung of the progressive Justice Party are also expected to soon follow suit. (Yonhap)