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.

As the president awaits an impeachment trial, the country’s interim leader may, too, be ousted. The currency has plunged as the crisis has deepened.

South Korea’s parliament voted to impeach prime minister and acting President Han Duck-soo Friday, less than two weeks after parliament stripped President Yoon Suk Yeol of his powers over his short-lived martial law order that plunged the country into political chaos.