Boris Johnson’s hopes of securing an election on his own terms appear to be fading as opposition parties continue to resist a vote before the prospect of a no-deal Brexit on October 31 is eliminated.

The Prime Minister is back on the campaign trail for the election he is yet to successfully call after a torrid day in which his brother resigned from Government while describing being torn between family and “the national interest”.

The Prime Minister’s visit to Scotland came as Labour’s Jeremy Corbyn and other Westminster opposition leaders were holding talks about their approach to the timing of an election.

Labour, the SNP and Liberal Democrats could refuse to back the PM’s second attempt to get an early election on Monday, because of concerns the poll should be delayed until a Brexit deadline extension has been secured.

The Prime Minister has said he wants polling day to be October 15, but in order to call the snap election he needs a two-thirds majority in the Commons and opposition parties do not trust him to stick to that date.

They also have concerns about whether he will comply with the cross-party legislation due to be passed by the House of Lords on Friday which would require him to seek a delay to Brexit if there is not a deal in place by October 19.

Mr Johnson used a rambling press conference on Thursday to say he would rather be “dead in a ditch” than ask for a further delay.

Shadow foreign secretary Emily Thornberry said his comments were an indication of how the Prime Minister was “as slippery as can be” and could not be trusted over the timing of polling day.

“If we vote to have a general election then, no matter what it is that Boris Johnson promises, it is up to him to advise the Queen when the general election should be,” she told BBC Radio 4’s Today programme.

“We have a Prime Minister who is so unlike any other prime minister that we have had. In the past, if you passed a law you could be pretty sure the prime minister will abide by that law.

“But we heard from the Prime Minister’s own mouth that he will die in a ditch – obviously I hope he doesn’t, but I actually hope he would obey the law.”

SNP Westminster leader Ian Blackford told Sky News: “We have to be careful that we don’t walk into a trap.

“I want the removal of Boris Johnson. I want an election. But we’ll do it in a way that there are not unintended consequences.”

He added that Mr Johnson “is not going to compel parliamentarians to give him a mandate to determine the timing – we don’t trust him”.

The PM’s continued campaigning comes after a day of unwelcome events saw Jo Johnson quit as a senior minister attending meetings of his brother’s Cabinet.

The pro-EU younger Johnson described facing “unresolvable tension” and being “torn between family loyalty and the national interest”.

Mr Johnson was using his visit to Aberdeenshire to announce that Scottish farmers will receive an extra £51.4 million over the next two years, in addition to the £160 million announced in Wednesday’s spending round.

He will also make the traditional prime ministerial trip to the Queen’s Balmoral estate on Friday but the visit will be shorter than expected due to the political turmoil in Westminster.

The Prime Minister will stay at the castle on Friday night before returning to London on Saturday.

His girlfriend Carrie Symonds is expected to accompany him on the Balmoral trip.

There were also further signs of unease within the Tory ranks about the uncompromising Brexit stance which saw Mr Johnson boot 21 senior Conservatives – including former chancellors Ken Clarke and Philip Hammond – out of the party in the Commons by removing the whip.

Former defence secretary Sir Michael Fallon, who is standing down as Tory MP in Sevenoaks, said he hoped an appeal mechanism would be put in place for his former colleagues.

He added: “I also worry that it sends the wrong message to remainers – particularly in my party.

“I think, by definition, some five million Conservatives must have voted remain and we have got to be very careful not to drive them into the hands of remainer parties like the Liberal Democrats in England or the Scottish nationalists in Scotland.”

David Hughes is PA Political Editor.