The ruling Saenuri Party kicked off negotiations Friday to defuse an escalating row over how to pick its presidential candidate after underdogs in the race threatened to bow out en masse unless primary rules are changed first.

At issue is a demand from three minor contenders -- Gyeonggi Province Gov. Kim Moon-soo and Reps. Chung Mong-joon and Lee Jae-oh -- that the party fully open the primary voting to non-party members in what is dubbed an "open primary" system.

They claim the current rules are favorable to former party chief Park Geun-hye, and without changing them, they stand little chance of beating the long-time favorite and winning the party's ticket for December's presidential election.

Party leaders, considered close to Park, however, are opposed to the demand.

Under the current rules, the party's presidential candidate is determined based on a combination of votes, roughly half from party members and the other half from ordinary citizens. Minor contenders have called for determining the winner based entirely on votes from ordinary citizens.

On Friday, party chief Hwang Woo-yea and secretary general Suh Byung-soo held a breakfast meeting with representatives of the three candidates to discuss the issue. But prospects for a breakthrough appear slim as the differences between the two sides are too wide.

"We have to hold the primary in a way that is great, productive and helpful to the people ... so that we can show the people that we are a party the people can rely on at a time when the nation is in difficulty and hardship," Hwang said at the start of the meeting.

Details of the meeting were not immediately available, but the representatives of the three candidates were expected to stick with their demand for an open primary.

The meeting was also expected to discuss setting up a negotiating body on the issue. But agreement on that does not appear easy as party leaders want to put it under official party organs, such as the Supreme Council. The three sides, however, want it to be an independent body. (Yonhap News)