The two left-leaning candidates in South Korea's three-person presidential race have agreed to start talks on picking a single candidate to take on conservative front-runner Park Geun-Hye.
Software mogul Ahn Cheol-Soo, an independent, and main opposition candidate Moon Jae-In will meet Tuesday to discuss their options, officials from both their campaigns confirmed.
The move had been widely expected, with Ahn and Moon seen as splitting the liberal vote and handing the presidency to Park if they both stay in the race until polling day on December 19.
While polls have consistently shown a clear win for Park -- the daughter of former military strongman Park Chung-Hee -- in a three-way race, they have her neck-and-neck in a face-off with either Ahn or Moon.
"I believe we must be unified to achieve a change in government," Ahn told reporters during a visit to the southwestern city of Gwangju.
"Moon and I share common values and philosophies and I hope we can agree on political reforms," Ahn said.
Moon's camp has been vocal on the need for a unified candidacy while Ahn's side has been more cautious, insisting on a commitment from Moon's Democratic United Party to political reform.
Ahn has virtually no political experience but is enormously popular with young liberal voters, who see him as untainted by corruption or by political or commercial abuse of power.
Although courted by politicians across the political spectrum, he has remained without party affiliation despite an obvious empathy with the liberal opposition.
Ahn has repeatedly attacked predatory capitalism and called for the overhaul of an economy dominated by a few powerful conglomerates, known as "chaebols".
Moon's supporters argue that their man would make the better candidate as he has the party base necessary for the president in dealing with parliament.
Moon, a human rights lawyer and former pro-democracy activist, is best known for serving as a top aide to then-president Roh Moo-Hyun, who committed suicide in 2009.