Liberal candidates Moon Jae-in and Ahn Cheol-soo were struggling Thursday to narrow their differences in their stalled talks on how to pick a joint candidate for the Dec. 19 presidential election.

The Democratic United Party’s Moon and independent Ahn met at a hotel in Seoul in the morning to try to hammer out an agreement that has so far eluded their negotiators.

They failed to yield any results from the one and half an hour session, which was proposed by Moon during their live television debate on Wednesday night.

“Every effort needs to be made in the remaining time,” Moon said after attending a photo exhibition at Sangmyung University in Seoul in the afternoon. He declined to comment further, saying only that other commitments have been put aside to make time for the issue.

Following the meeting, Moon’s campaign spokesman Park Gwang-on said that nothing had been achieved and that the candidates were unable to “narrow their differences even by one step.”

Ahn’s aides said that he had canceled his appointments for the day to have “a time of reflection.”

Since the stalled talks over the unified candidate selection method were revived in a one-on-one meeting between Ahn and Moon on Sunday, the two sides have clashed over a number of issues regarding the opinion poll.

Although the two sides had discussed a number of methods for candidate selection, the options were narrowed down to conducting an opinion poll, with the time running out for candidate registration on Nov. 26.

Under the agreement between the two sides announced on Nov. 6, when the merger plans were first announced, the unified candidate must be selected before the final registration date.

The main issue the two sides differ on is the wording of the survey question.

Ahn’s side favors asking respondents who they think would win against the Saenuri Party’s presidential candidate Park Geun-hye, while Moon and the DUP have maintained that the question should be designed to single out the individual that best represents the progressive bloc.

The two sides’ positions are thought to be a reflection of various survey results, which show that Ahn has higher ratings that Moon when pitted against Park, but the DUP candidate has stronger support as the progressive coalition’s candidate.

Gallup Korea’s polls for the third week of November showed that Ahn received 46 percent support while Moon was given 44 percent support in the scenario where each candidate competed with Park in a two-way race.

However, 45 percent of the respondents picked Moon when asked who they felt was more suited to represent the Ahn-Moon coalition. Ahn’s figure came in at 35 percent.

The two sides’ differences were also clearly visible during the late night TV debate held the day before, despite agreeing on the need for the coalition, and their desire to bring about a change of administration.

“Judging who will beat Park is part of the unification process, and that standard should be who receives more support from the members of the public who want a change of administration,” Moon said on Wednesday.

Ahn, however, reiterated that the candidate who would be sure to beat Park should be selected, not the chief of the progressive bloc.

“(Selecting the candidate) who will be considered against Park at the very moment of voting. I think this is the better way,” Ahn said.

By Choi He-suk  (cheesuk@heraldcorp.com)