Under the Constitution of Pakistan, the prime minister is elected by a majority of the lower house National Assembly, which has 342 members.
A candidate needs a majority of legislators, 172, to vote for him to become prime minister. That is the same number of votes against him in a no-confidence vote needed to oust him and dissolve his cabinet.
So if PM Imran Khan could survive a no-confidence vote even if he got fewer votes than the opposition but only if the latter did not get the 172 votes that make up a majority in the 342-seat house.
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WHAT HAPPENS AFTER THE VOTE?
If PM Imran Khan loses the vote, parliament can continue to function until its five-year tenure ends in August 2023, after which a general election is due within 60 days.
There will be a vote in the National Assembly to elect a new prime minister to serve until then. Candidates can be put forward by any party with legislators in the assembly.
The new prime minister can, however, call a general election immediately, without waiting until 2023.
Some constitutional analysts say the assembly can be dissolved and a general election held if no candidate can secure a majority of votes to become the prime minister.
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WHAT IS THE TIMELINE OF THE VOTE?
Opposition parties filed the no-confidence motion in early March, and it was presented and tabled before the National Assembly on Monday.
The speaker of the National Assembly has to carry out the vote no sooner than three days and no later than seven days after the motion is tabled.
The earliest the vote can happen is Thursday. The latest, by most accounts, is Monday.
