Opposition politician Shehbaz Sharif submitted his nomination to be Pakistan's next prime minister to the legislature on Sunday, his party said, after incumbent Imran Khan lost a no-confidence vote in parliament after nearly four years in power.

The younger brother of three-time prime minister Nawaz Sharif, Shehbaz (above), 70, has led a bid by the opposition in parliament to topple former cricket star Khan, and he is widely expected to replace him following a vote on Monday.

But Khan's party also submitted papers nominating the former foreign minister as a candidate, saying their...