The Democratic United Party pushed ahead with its second primary vote in the southeastern city of Ulsan on Sunday despite the boycott of the election by three of the four contenders.
Representative Moon Jae-in won the Ulsan race with 52-percent, while former South Gyeongsang Governor Kim Doo-kwan gained 32-percent.
But three candidates-- Kim, Sohn Hak-kyu and Chung Sye-kyun -- did not show up for the Ulsan vote, saying that the rules for mobile voting unfairly gave Moon Jae-in a landslide victory in the first primary election on Jeju on Saturday.
In the Jeju race, Moon secured nearly 60-percent support while former party chairman Sohn Hak-kyu was a distant second with 21-percent.
Overall results are determined by delegates and the public who vote by physical ballot or by mobile phonewith mobile phone accounting for the biggest bloc of the votes in both the Ulsan and Jeju races.
The complaints focused on the requirement that votes made by mobile phone are not counted unless each voter listens to the entire automated message listing the names of all four contenders.
On the pre-recorded message, Moon is last on the list with Chung, Kim and Sohn listed first, second and third.
Supporters of Sohn and Kim argued that many of the votes cast for the two contenders were ruled invalid because voters ended their calls before the entire message was heard.
And there was no message warning voters that their ballot would be invalid if they ended the call early.
Critics say this problem with the mobile voting system was reflected in the lower than expected voter turnout in the Jeju race.
In response, the DUP leadership announced Sunday that it will locate voters whose mobile votes were disqualified and give them another chance to vote.
And the party offered to postpone the next scheduled vote for Gangwon Province to Monday with a clearer message for mobile voting procedures.
However, the trio said the measures were inadequate and demanded the party create a new election management system in which delegates for each candidate can participate.
Kim Yeon-ji, Arirang News.