South Korea's two left-leaning presidential hopefuls on Monday resumed talks aimed at uniting behind a single candidate to take on conservative front-runner Park Geun-Hye.
The talks were suspended last week after independent Ahn Cheol-Soo accused Moon Jae-In, candidate of the main opposition Democratic United Party (DUP), of lacking commitment to political reform.
Ahn and Moon only have one week to decide which one of them will drop out of the race and support the other, with the deadline for candidate registration falling on November 26.
Ahn agreed Sunday to resume merger discussions following the resignation of the DUP chairman and eight other senior party officials whom he insisted were a stumbling block to political reform.
"Both sides must show they are ready to engage in new, fresh politics," Ahn said during a briefing for foreign reporters in Seoul on Monday.
If the two men fail to reach agreement and both end up running in the December 19 ballot, they will split the liberal vote and effectively hand the presidency to Park.
While polls suggest Park, from the ruling New Frontier Party, would easily win in the event of a three-horse race, they put her neck-and-neck in a face-off with either Moon or Ahn.
If a merger is agreed, Ahn said he was "confident that the likelihood of defeating candidate Park is very high".
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.
Moon's supporters argue that their man would make the better candidate as he has the party base and political experience necessary for the president in dealing with parliament.