Mr. Sharif, whose family has been dogged by accusations of graft for decades, was selected by Pakistan’s Parliament at a time of deep political divisions and economic tumult.
Imran Khan’s actions have set up a constitutional battle over the country’s leadership. The Supreme Court is expected to address the turmoil on Monday.
Prime Minister Khan, who faces the prospect of being removed from office by Parliament, accused the United States of mounting a conspiracy to topple his government.