The presidential hopeful for the minor progressive party withdrew her bid Monday and endorsed the main opposition candidate running for the December election.

Rep. Sim Sang-jung of the Progressive Justice Party (PJP) said she was quitting and hoped such a move could help rally support around one liberal candidate.

"I hope people will support Democratic United Party (DUP) candidate Moon Jae-in, who is effectively representing the liberal opposition camp," she said at a news conference held at the National Assembly. She said such a move is needed to bring about change in the country's government.

Party sources said Sim had made no preconditions for her actions, and did not say she would join Moon's election campaign team.

"There will be a need to determine what joint policy measures can be pursued together," a PJP insider said.

The decision by the 53-year-old lawmaker comes just 23 days before the public goes to the polls to pick the country's next president on Dec. 19.

Her resignation also comes after independent contender Ahn Cheol-soo last week quit the race so the liberal camp can field just one candidate to compete with ruling Saenuri Party's standard-bearer Park Geun-hye.

With Ahn and Sim out of the race, the liberal camp will be represented by Moon and splinter progressive Advancement and Unification Party candidate Lee Jung-hee. (Yonhap News)