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-times Prime Minister Nawaz Sharif, Shehbaz, 70, has led a bid by the Opposition in Parliament to topple 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 members of Parliament would resign en masse should he lose, potentially creating the need for urgent by-elections for their seats.

On Sunday, Khan repeated allegations that a foreign conspiracy was behind the regime change. “The freedom struggle begins again today,” he tweeted.

His government fell in the early hours of Sunday after a 13-hour session. Opposition parties were able to secure 174 votes in the 342-member house, giving them the majority they needed to enable the vote to elect a new Premier.