The prosecution on Friday asked Rep. Koh Seung-duk of the ruling Grand National Party to show up at the Seoul Central Prosecutors’ Office Sunday to explain his allegation of vote-buying during party’s past leadership election.

Koh’s testimony is expected to shake the ruling party, which is now undergoing major leadership reformation to woo voters ahead of the April 11 general election and Dec. 19 presidential election.

According to investigators, the summons came a couple of days after Koh divulged that he received an envelope with 3 million won ($2,600) from a close aide to one of the leadership contenders ahead of a party convention between 2008 and 2010. Koh said he had returned the money. The candidate won the chair post and belongs to a faction loyal to President Lee Myung-bak, he said.

The GNP immediately referred the case to the prosecutors, fearing voter sentiment ahead of important elections.

According to Koh’s claims, the person who attempted the bribery was one of the four previous GNP leaders, Reps. Park Hee-tae, Chung Mong-jun, Hong Joon-pyo and Ahn Sang-soo. Koh denied that the culprit was Hong, while Park, Chung and Ahn denied involvement.

Kim Hyo-jae, a senior secretary for state affairs to Lee, dismissed the rumors that he was the deliverer of the bribe on behalf of Park.

“I haven’t exchanged a word or a look with Koh since the 18th National Assembly kicked off in 2008,” he said.

Tensions are high that the scandal could deal a severe blow to a party already staggering over corruption and criminal allegations. The party has recently transitioned into crisis management mode, calling on former chair Rep. Park Geun-hye to lead them. 

Park has vowed to deal with the problem sternly.

“The scandal could destroy what the party has built over the years. This could provoke hatred toward our party,” a lawmaker was quoted as saying to the Yonhap news agency.

In fear of losing more face publicly, the party sought to dampen rumors.

“We would like to offer our apology to the public,” said Rep. Hwang Yeong-chul, the party’s spokesperson, at a radio show Friday morning.

Under current law, those who orchestrate cash-for-vote schemes in a political party’s elections can be sentenced to up to five years in jail or fined up to 10 million won.

By Bae Ji-sook (baejisook@heraldcorp.com)