He made stops in Incheon and Ansan, both lying just west of Seoul, before returning to the capital for the evening.

Thirteen candidates are vying for the presidential office, with two having dropped out, but this has essentially been a five-horse race.

The latest poll on the presidential election published Wednesday showed Moon in the lead with 42.4 percent, followed by two runners-up -- Ahn Cheol-soo of the center-left People's Party and Hong Joon-pyo of the former ruling Liberty Korea Party -- tied at 18.6 percent.

The other major candidates included Sim Sang-jeung of the progressive Justice Party, who in the latest poll stood in fourth place with 7.3 percent, and Yoo Seong-min of the splinter conservative Bareun Party with 4.9 percent.

The candidates made their cross-country trips amid the worst fine dust of the year. A dozen cities and counties were placed under fine dust warnings earlier in the day, as dusty air flew in from the deserts in southern Mongolia and northern China on a strong wind overnight.

Hong was in the capital region in the morning, and then spent his afternoon in Gongju, South Chungcheong Province, to rally conservative voters in the swing region.

Ahn took his campaign to Gwangju, the long-time liberal stronghold in the southwest, and covered populated areas in the metropolitan city some 330 kilometers from Seoul.

Yoo reached out to sports fans, first at Suwon World Cup Stadium in Suwon, Gyeonggi Province, for a pro football match and then Jamsil Stadium in Seoul for a baseball game, before visiting southern Seoul neighborhoods.

Sim visited Seoul Grand Park in Gwacheon, just south of the capital, to greet picnic goers in the morning and returned to the busy Gangnam Station in southern Seoul to target young voters.

In the first early voting for a presidential election held on Thursday and Friday, 11.07 million people, or 26.06 percent of the electorate, cast their ballots. (Yonhap)