The Westminster leader of the Scottish National Party (SNP) Ian Blackford criticised fellow opposition MPs on Tuesday for their inability to come together and choose a potential Prime Minister to replace Boris Johnson if a motion of no confidence were to be successful in the House of Commons.
The leader of the SNP's 35 representatives in parliament, accused MPs from other party's of "failing to recognise the challenge" of a no deal Brexit while talking to BBC's Good Morning Scotland.
"The opposition parties have worked well together and all supported the Benn Act which forbids a no-deal Brexit at the end of the October," he said.
The challenge that we face is that we've got a Prime Minister who will stop at nothing. He's still threatening to leave on a no-deal Brexit despite that being unlawful. I would say that if we want to guarantee that Boris Johnson is not going to try and take us out on a no-deal basis then we have to take the keys of Number 10 away from him," Blackford added.
He urged opposition leaders to unite and "put someone in [Number 10] on a caretaker basis, that will write the letter extending Article 50 then we will have an election. I say to colleagues if we fail to do this, then there is a risk that Boris tries to crash out and that will be a failure of leadership."
The comments by Blackford on Tuesday come amid talks between what has been described as the "rebel alliance" begin to stall. He also described that whoever the new Prime Minister installed by the opposition would be, would only serve in an "administrative" function.
Referring to Labour's proposal that the opposition leader Jeremy Corbyn should be tasked with forming a government, Blackford said: "We're happy to look at any candidates. Jeremy is the leader of the opposition and there has to be a prospectus (sic) that he can command a majority."
Later on Tuesday however, Labour Party Shadow Chancellor John McDonnell told reporters that the main opposition is unlikely to table a no confidence motion in the government until after a European Union summit later in October.
McDonnell said that remain inclined Conservative and former Conservative MPs will be waiting to see the contents of Johnson's deal before deciding to vote to bring down his government.
"You have to go at the pace of the coalition" McDonnell said reporters.
"A large number of people among the 21 Conservatives will obviously want to see whether Boris Johnson brings back a deal of some sort and, secondly, has he then submitted some application for extension".
However, he explained failing that, the opposition should "coalesce around another individual, and we're not being precious about who that is."
Traditionally if the largest party in parliament, which remains the Conservatives at this point, fails to form a government, it is the duty of the leader of the opposition to form a government.
However, the opposition politicians of varying ideological persuasions, have been unable to agree on who should replace Johnson if the Conservative government were to be toppled.
Despite support from the SNP and Welsh nationalist party Plaid Cymru, Liberal Democrat leader Jo Swinson claims that Corbyn is not the "unifying figure" capable of uniting ex-Tories, Liberals, and Independents.
The Prime Minister would be tasked with sending a request to the EU to request an extension to Article 50 and therefore Britain's ultimate departure date from the EU, currently scheduled for 31 October.
Currently, parliamentary legislation known as the Benn Act restricts the Prime Minister from leaving the EU without a Withdrawal Agreement and if he fails to present a deal to parliament, he is required by law to ask for an extension beyond the deadline of 31 October.
More Than One Way To Oust A Prime Minister?
Traditionally, a Prime Minister is removed through losing a general election. Attempts by Boris Johnson to break the parliamentary log-jam through an election have been blocked due Fixed Term Parliament Act (FTPA) which requires at least 2 thirds of MPs to vote for it.
Any MP can table a motion of no confidence in the government however. If a majority of MPs vote for said motion, the FTPA outlines a 14-day period within which a a new government can be formed. If the largest party fails to do so, the task falls to the 2nd largest party, in this case Labour which is led by Mr Corbyn.
However, in order to get a functioning majority, Labour would need support from various opposition parties in order to command a working majority.