“On some issues, we have come closer to bridging the gap, but there are other issues that we need to continue discussing. ... We need to discuss more thoroughly amongst the lawmakers on how to sign them into law,” said Moon on Monday in a joint press conference with Kim.

Coinciding with the Chuseok holiday, the two leaders’ unexpected agreement reflected a shared interest between them who have both struggled to calm pushbacks from members of rival factions amid constant infighting over elections rules, observers said.

The pledge for open primaries being one of his major political platforms, Kim has been challenged by lawmakers loyal to President Park Geun-hye. They have questioned his push for open primaries as an attempt to widen his political clout and pressed him to abandon the attempt.

Mindful of such calls, Kim convened a Supreme Council meeting Tuesday morning to explain his meeting with Moon, but some of the pro-Park members boycotted the session.

Moon, who survived heavy in-house fighting over his party’s reform measures and his proposal of a vote of confidence last week, has been faced with mounting pressure to prove his leadership by implementing his reform initiative, one of which is a poll to survey ordinary citizens by telephone.

Despite the rare bipartisan breakthrough, prospects of the agreement being implemented remained to be seen as party members, particularly those from the Saenuri Party, are likely to oppose the agreement.

Among those critics are Rep. Cho won-jin of the ruling party, a Park loyalist. Cho publicly denounced the agreement, saying that Kim had given in to the demand of the NPAD which has lost to the Saenuri Party repeatedly in latest elections.

“I think the agreement is incomplete and unspecific,” said Cho in a media interview. “Chairman Kim was manipulated by the NPAD. What we are seeing is the party which had won the latest elections agreed to the demand of the party which had lost the latest elections,” said Cho.

By Yeo Jun-suk  (jasonyeo@heraldcorp.com)