The frontrunner to replace South Korea's ousted leader Park Geun-hye has pledged to "embrace" communist North Korea. Moon Jae-in is currently leading in the polls to elect a new South Korean president which are expected to take place in May.

A Realmeter survey this week put Moon on 36.1%, with his nearest rival, acting president Hwang Kyo-ahn lagging behind at 14.2%.

"If the power of candlelight has brought us this far, we now have to work together for a complete victory," Moon said at a news conference on Sunday (12 March), referring to weekly candlelit vigils calling for Park's impeachment. "South Korea will make new history through a regime change."

Moon takes a less strident view than impeached president Park, who was known to take a hard line against the Pyongyang regime. He told journalists that his country needs to work with neighbouring country North Korea.

"We must embrace the North Korean people as part of the Korean nation, and to do that, whether we like it or not, we must recognise Kim Jong-un as their ruler and as our dialogue partner," Moon said.

The 64-year old trained as a lawyer and has supported human rights and civil rights abuse challenges.

He was the former chief of staff to late President Roh Moo-hyun. Moon received the nomination for the Democratic United Party's candidate for the presidential election in 2012, but lost to Park Geun-hye.

The rancour between Moon and the ousted president goes back many years. In 1975, Moon was jailed for taking part in street demonstrations against Park's father and he has criticised her as "very authoritarian and regressive".

As the chairman of the Minjoo Party of Korea, a social liberal party, many are hoping that Moon can bring together right and left-wing factions.

Woo Jung-yeop, of the Asian Institute for Policy Studies, said Moon had managed to portray himself as a moderate and rational leader who has the backing of the younger generation.

"He is a liberal champion with good chances of winning the next presidential election," Park Kie-duck, former head of the private Sejong Institute told the China Morning Post.

Moon has pledged to clamp down on the economic power held by the chaebol, a large family-owned business conglomerate, which Park's ties to became a political scandal that led to her impeachment.

Political experts have criticised Moon's political inexperience and doubt his toughness in world politics.

"He lacks political acumen. He is too soft to cope with the dirty games in realpolitik," Kie-duck said.

Disgraced leader Park has returned to her home after leaving the presidential palace on Sunday. It's expected she will face an investigation into her alleged collusion with a confidante to extort money from companies. She has apologised for "failing to fulfil my duty as president".