South Korea's ruling Saenuri Party decided Monday to expel two of its members involved in a money-for-nomination scandal, a major setback for the party ahead of the December presidential election.

Hyun Young-hee, elected as a proportional representative in the April general elections, is under suspicion she gave some 300 million won (264,300 U.S. dollars) to Hyun Ki-hwan, a former member of the ruling party's nomination committee, to win the nomination.

"The reason for the expulsion is because the two damaged the party and tarnished its reputation," Kyung Dae-soo, head of the party's ethics committee, reportedly said during a briefing.

The latest scandal, though still under investigation, is a blow to the Saenuri Party after it managed to eke out an election victory in April despite a series of corruption scandals that shook the conservative party.

It can also damage the image of Park Geun-hye, the unrivaled presidential front-runner on the conservative ticket, and hurt the ruling party's chances of winning the crucial poll on Dec. 19.

Park's rivals, including three Saenuri presidential hopefuls, say Park is responsible for the nomination process she had overseen as the interim party head.