Kim Han-gil, 60, a four-term lawmaker, was elected as the new leader of the Democratic Party, formerly the Democratic United Party, defeating his main rival, Rep. Lee Yong-sup, Yonhap news agency reported.
The center-left party has suffered a number of election defeats, including December's presidential vote and last month's by-elections in which the party failed to win a single seat.
At its convention Saturday, the party pledged to move toward centrist policies and carry out intra-party reforms, in an effort to win more public support.
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