Presidential front-runner Moon Jae-in embarked on a campaign trail Tuesday by paying his respects to the country's late leaders.

Moon, who won the nomination of the liberal Democratic Party a day earlier, visited a national cemetery in Seoul to pay tribute before the tombs of former Presidents Syngman Rhee, Park Chung-hee, Kim Dae-jung and Kim Young-sam.

"The Republic of Korea has had many ups and downs since its foundation, and our past presidents have had their successes and failures, but it is a history we must embrace, and it is our task to overcome the successes and failures," the nominee said.

In South Korea, it is customary for politicians to visit the graves of past leaders to mark the start of a new journey. Some politicians, however, choose to honor only those whose legacies they see fit to respect.

"I made a promise with myself to achieve national unity in a just manner on the foundation of fairness and justice," Moon told reporters after visiting the graves of all past presidents.

"The Republic of Korea has many deep-rooted evils in the shadows of its rapid growth, and our people recently saw the bare face of those deep-rooted evils," he said, referring to a massive corruption and influence-peddling scandal that led to the ouster of President Park Geun-hye last month. The impeachment triggered an early election on May 9.

Moon later met with party lawmakers at the National Assembly before traveling to Gimhae, 449 kilometers southeast of Seoul, to visit the tomb of his political mentor and late former President Roh Moo-hyun. (Yonhap)