By Daniel J. McLaughlin
If a vote of confidence is called, and Boris Johnson loses it, an alternative government may be formed.
As leader of the opposition, Jeremy Corbyn believes he should lead the caretaker government, uniting the opposition parties - Labour, the SNP, the Lib Dems, Plaid Cymru, the Green Party - as well as other independent MPs.
But not everyone is convinced, with other names - such as Labour's Harriet Harman and Tory Kenneth Clarke - suggested for the role.
The Labour leader has the support of Caroline Lucas, who says it is "entirely right and proper" for him to form a caretaker government.
However, Lib Dem MP Chuka Umunna argues that Corbyn does not have the numbers to do so.
Caroline Lucas says that Jeremy Corbyn has her "full support" to lead an emergency caretaker government, if Boris Johnson is ousted as prime minister.
The Green Party MP told the i: "He does have my full support. I think, as the leader of the opposition, it's entirely right and proper he is given the first opportunity to form a caretaker government and I would certainly support him in doing that.
"But I also recognise there are voices around the House saying they won't and, therefore, I think it's important that we have a discussion about who else might be acceptable - if it's the case that Jeremy Corbyn isn't able to secure that majority."
Lucas said that Jo Swinson may be reluctant to back her Labour counterpart, because the Lib Dems are contesting seats in largely Tory-held constituencies. She explained that "what Jo doesn't want is for people to say 'vote Lib Dem and get Corbyn'".
She added: "I think the bigger issue right now is the national interest so I wish she would support Jeremy Corbyn and I've publicly called on her to do so."
However, Chuka Umunna argues that the Lib Dems are not standing in the way of Corbyn leading caretaker government - the Labour leader's numbers are.
In an article for the Independent, the Lib Dem MP accuses senior Labour figures - such as John McDonnell and Diane Abbott - of "peddling the myth" that Corbyn could form a government, if the Lib Dems support him.
Umunna, a former Labour frontbencher and an ex-Change UK MP, argues that "this is nonsense and they know it".
He writes: "Whatever claim he may have to lead such a government, and notwithstanding whatever we do, the Labour leader does not have the numbers in parliament to form such an administration.
"Former US president Lyndon B Johnson famously said that the first rule of politics was being able to count – senior Labour folk are struggling to do so here."
He explains that even with the Lib Dems' support, Corbyn would be short of a majority. All but one of the Tory rebels and a number of independent MPs have said they will not support the Labour leader under any circumstances.
Umunna concludes: "In short, remaining in the EU is not a cause for which Corbyn is prepared to put the national interest before his party political interests.
"That’s what’s really going on here – the rest is noise."
Under the Fixed Term Parliaments Act, if the government loses a vote of confidence, there is a 14-day period where a government or an alternative government can unite and command a majority in the Commons.
If they fail to do so, a general election must be called.
There are 650 MPs in the Commons - and to command a majority, a government needs 326 MPs on their side.
The Labour Party currently has 244 MPs, and if it joins together with the SNP (35), Plaid Cymru (four) and the Green Party (one), it would still be short by 42 MPs.
Even with the support of the 19 Lib Dem MPs, there would not be enough for a parliamentary majority.
Despite these numbers, Corbyn said that the caretaker government would be "strictly time-limited". His first step would be to seek an extension to the Article 50 process to prevent a no-deal Brexit.
After delaying Britain's departure from the EU, the Labour leader would call a general election.