SEOUL—South Korea’s legislature voted to impeach acting President Han Duck-soo on Friday after he declined to make judicial appointments needed to advance the impeachment of his predecessor, extending the political upheaval that began with a short-lived martial law declaration earlier this month.

Han has been the caretaker leader after President Yoon Suk Yeol was impeached by the assembly over his short-lived imposition of martial law earlier this month.

The vote intensifies a political crisis as the Constitutional Court meets for its first hearing on suspended President Yoon Suk Yeol's short-lived martial law.