Douglas Ross has not called for Boris Johnson confidence vote

Douglas Ross has not re-submitted his letter of no confidence in the prime minister, BBC Scotland understands.

Boris Johnson will face a vote of confidence in his leadership later, after a number of Conservative MPs said they no longer wanted him to carry on.

However, the Scottish Conservative leader - who previously called for Mr Johnson to go and then rescinded - has not yet backed the move.

The Scottish Secretary, Alister Jack, said the PM had his full support.

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On Monday morning, the chairman of the 1922 Committee of Conservative MPs confirmed a vote of confidence in Mr Johnson would be held later.

A vote is triggered when at least 15% of sitting Tory MPs write to the committee chairman - currently Sir Graham Brady - saying they no longer have confidence in their leader.

There are 359 Conservative MPs, which means at least 54 have sent letters of no confidence.

Sir Graham Brady told reporters that the threshold had been reached over the weekend and a vote would be held on Monday between 18:00 and 20:00.

Mr Johnson made his case about why he wanted to stay on as leader before Tory MPs shortly after 16:00.

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In January, Douglas Ross wrote to ask for a confidence vote over the Partygate scandal.

But he withdrew his letter again in March when war broke out in Ukraine.

Last month, when Sue Gray's report into Downing Street parties was published, Mr Ross said he still believed Boris Johnson should remain as PM.

He said toppling him would cause instability that would benefit Putin, but added the PM would still have to go if an inquiry found he had misled parliament.

Mr Ross confirmed on Monday that he had not resubmitted his letter of no confidence.

He has yet to say whether or not he will back Mr Johnson in the vote, but is expected to set out his position after the PM has addressed MPs.

The result of the secret ballot will be declared at about 21:00.

Mr Jack (left) is continuing to back the prime minister

Scottish Secretary Alister Jack has already thrown his support behind the prime minister.

He said: "The prime minister has my full support, and I will be voting to back him tonight.

"He is showing tremendous leadership as we face major challenges at home and abroad.

"I have no doubt that my colleagues in the parliamentary party will vote to show their confidence in the prime minister."

Former Scottish Tory leader Ruth Davidson has previously said Mr Johnson's position was untenable.

On Monday, she shared a letter from Tory MP Jesse Norman to the PM, stressing "how right [Mr Norman] is".

In the letter, Mr Norman sets out his reasons why he can "no longer" support the PM - which include accusing Mr Johnson of presiding "over a culture of casual law-breaking" in relation to Downing Street parties.

'Flip-flop'

Scottish Tory MSP Murdo Fraser urged MPs to oust Mr Johnson, adding the country should have a "fresh start" under a new leader.

And fellow Tory MSP Jeremy Balfour said he did not have confidence in the PM either.

SNP Westminster leader Ian Blackford said Mr Johnson was not fit to be PM, and "there cannot be any more flip-flopping from Douglas Ross and the Scottish Tories". He said Scottish Tory MPs had shown "craven loyalty to Boris Johnson".

Scottish Labour leader Anas Sarwar said Douglas Ross had to stand up to Boris Johnson.

Scottish Greens co-leader Patrick Harvie said Mr Ross, and his colleagues at Westminster, had "to finally do the right thing and bring an end to Boris Johnson's utterly inept premiership".

Scottish Lib Dem leader Alex Cole-Hamilton said Mr Ross and other MPs had shown a lack of courage and decency by failing to oust him.

This vote is a dilemma for the leader of the Scottish Conservatives, Douglas Ross, who gets a say as MP for Moray.

Should he keep backing a lawbreaking PM that the Scottish party officially blames for heavy losses in the recent local elections?

Or should he abandon Boris Johnson despite having repeatedly said he should continue to lead the UK through the Ukraine crisis?

He faces embarrassment either way and abstaining would probably make him look weaker than the other two options.

Mr Ross has already said the PM should go after the war and would have "little option" but to quit, regardless of the international situation, if a Commons committee finds he knowingly misled parliament.

He could continue to defer to these scenarios in an effort to be consistent with his most recently expressed position.

Or he could argue that the very fact there's a confidence vote means circumstances have changed again - that perhaps the political stability he seeks is no longer achievable under Boris Johnson.

Mr Ross is expected to set out his decision probably after he's heard the PM's address to Tory MPs this afternoon.