The minor opposition Justice Party on Tuesday picked first-term lawmaker Lee Jeong-mi as its new leader tasked with bolstering its legislative presence to support its core progressive supporters.

In the leadership election, Lee garnered 56.05 percent of the vote, beating former lawmaker Park Won-suk who received 43.95 percent.

Lee will succeed Sim Sang-jeung, the party's former presidential candidate whose two-year term ended this week.

In her acceptance speech, Lee vowed to strengthen internal cohesion to clinch an electoral win in the gubernatorial and mayoral elections slated for next June, and better support the civil society and labor circles, the party's core support base.

"(The election results) will lead to not only a leadership change, but also a strengthening of our leadership," Lee said. "I am ready to strengthen our unity to make our party one that is necessary for our citizens."

The new leader's inauguration ceremony is set to take place Thursday. (Yonhap)