Rep. Sohn Hak-kyu, chairman of the main opposition Democratic Party, feels the most heat from Moon Jae-in’s rise in political stature, but his aides say their potential rivalry will not harm the DP leader.

They hope that any competition between Sohn and Moon galvanized through next year’s parliamentary elections would see the whole opposition camp basking in a synergy effect.

“We expected the approval rating for Sohn, which soared after the April 27 by-elections, to decline in a couple months,” said DP lawmaker Park Seon-sook, who is in charge of planning Sohn’s presidential roadmap.

“My prediction is that both Sohn and Moon will see their public support increase to about 15 percent in the coming months, with neither of them gaining a decisive upper hand on the other.”

Critics say Sohn wasted an opportunity to consolidate his position as opposition frontrunner after winning a parliamentary seat in the latest round of by-elections, by failing to handle controversial issues in a firm manner. He was blamed for his flip-flopping stance over ratifying a free trade agreement with the U.S. and increasing subscription fees for state-run broadcaster KBS.

His lack of decisiveness reflects his delicate stance of having to walk a subtle line between centrists and progressives in the opposition fold to keep and expand support for his presidential bid, political observers say, adding that his maneuvering has so far been less than successful.

Aides to Rep. Park Geun-hye, the former GNP chairwoman who has been far ahead of other potential presidential contenders in a string of opinion polls, don’t see Moon’s rise as an immediate challenge to her second bid to become president. In a meeting with reporters in Daegu on Monday, GNP lawmaker Choi Kyung-hwan downplayed Moon’s emergence as “being designed just to boost the atmosphere” in the opposition camp.

By Kim Kyung-ho (khkim@heraldcorp.com)