What is a vote of no confidence?

Prime Minister Rishi Sunak is facing a potential leadership crisis, after Immigration Minister Robert Jenrick resigned over the government's plans to send some asylum seekers to Rwanda.

Senior Conservative Party figures have told BBC News political editor Chris Mason they would not be surprised if Mr Sunak ended up facing a no-confidence vote from his own MPs.

It's a vote in which MPs from all parties decide whether they want the government to continue. It can trigger a general election and see a new prime minister appointed.

While any MP can propose a no-confidence motion, there's no guarantee their request will be granted.

However, if the leader of the opposition - currently Labour leader Sir Keir Starmer - introduces the motion, convention means the government must provide parliamentary time for a debate.

The wording is usually: "That this House has no confidence in Her Majesty's Government."

The motion only needs a simple majority to pass: one more MP needs to vote in favour than the number voting against.

If the government wins, it carries on as before.

At present, the government has a majority of 58 in the House of Commons, so a lot of Conservative MPs would need to to vote against their own government for the motion to succeed.

If the government loses, two things could happen.

In normal circumstances, you would expect Parliament to be dissolved and a general election to be called.

It is also possible that the King could invite somebody else to form a government - someone who could win a vote of confidence in the House of Commons.

That would be very unusual.

It last happened in January 1924, when Stanley Baldwin's Conservatives decided to assemble a new Parliament rather than resigning, after losing their majority in a general election.

His government was defeated in a vote of no confidence and King George V asked Labour's Ramsay MacDonald - leader of the second biggest party - to form a government instead.

But almost a century later, it's not clear how that would work.

Conservative MPs could agree on a different leader themselves, whom the King could then invite to form a new government.

In principle, the monarch could even refuse to dissolve Parliament for an election.

Under the Lascelles principles (devised by Sir Alan Lascelles, private secretary to King George VI in 1950), the monarch could decline to do so if:

But these scenarios would put the monarch in a very difficult position, and it is not clear how they would play out.

If the government loses a confidence vote, the situation is similar to that of an election in which no one party wins a majority.

That means that the existing prime minister would only resign if it's clear someone else can command the support of the House of Commons.

However, if an alternative government is ready to take over, convention suggests that the PM should stand down.

But there is nothing clearly stated in law that says that they must do so.

Failing to step down would risk bringing the King into the dispute, as the monarch appoints PMs and, in theory, can dismiss one who behaves unconstitutionally.

It's very rare for a government to lose a no-confidence motion.

It has only happened once since World War Two.

That was in 1979, when the then Labour Prime Minister James Callaghan's minority government fell and was replaced by Margaret Thatcher's Conservatives at the subsequent general election.

Except for the period between 2011 and March 2022, when the Fixed-term Parliaments Act was in place, prime ministers have been able to call a general election whenever they want.

That means they can avoid a potential no-confidence vote by simply calling an election.