SCOTTISH Secretary David Mundell has denounced those resigning from the Cabinet over Brexit as “carpetbaggers” motivated by personal leadership ambitions.

Facing calls to quit himself from a fellow Scots Tory MP, Mr Mundell said he wasn’t going to be part of a “soap opera of resignations”.

Aberdeen South MP Ross Thomson suggested Mr Mundell should stand down after others quit saying Theresa May’s Brexit deal threatened the Union.

Read more: Brexit deal backlash: Live updates as Theresa May rocked by Cabinet resignations

In a WhatsApp message to Mr Mundell, Brexiter Mr Thomson said “no Unionist” could back the draft withdrawal agreement because it could leave Northern Ireland more closely bound by EU rules than the rest of the UK, creating a de facto border in the Irish Sea.

Mr Thomson said he was asking Mr Mundell "in the gentlest and strongest terms" to follow Mr Raab’s example.

At Holyrood, Nicola Sturgeon also mocked Mr Mundell for not resigning, after he and Scottish Tory leader Ruth Davidson previously said the Union was paramount to them both.

But speaking to ITV Border, Mr Mundell instead went on the offensive and ruled out quitting.

He said: “I believe that the best way of keeping the United Kingdom together is to ensure we have a deal as we leave the EU that delivers Brexit for Scotland and the rest of the UK.

“And that’s I’m focused on, not being part of some soap opera of resignations, and I’m not going to be bounced into resigning by carpetbaggers.”

It was reported yesterday that a factor in Mr Raab’s resignations was his undisguised desire to be Prime Minister should Mrs May be forced out.

Mr Mundell later repeated his criticism on the BBC: “As someone who has stood steadfastly for keeping Scotland in the United Kingdom, I am not going to take lectures from latter-day Unionists who are now using it as merely a hook on which to hang their resignations.

"The Union is far more important than people's political careers. That is why I am focused on Scotland remaining in the United Kingdom and the best way for that to happen is to ensure that we have an orderly Brexit across the whole of the United Kingdom."

Jackson Carlaw, the acting Scottish Tory leader, also used the term carpetbagger at Holyrood, suggesting a coordinated attempt to undermine Mr Raab’s credibility.

At First Minister’s Questions, Mr Sturgeon taunted the Tories over the Brexit crisis.

She said: “It is not so long ago that the Secretary of State for Scotland and the leader of the Scottish Conservatives said that, if there were to be separate relationships for the UK and Northern Ireland, they would resign. Where is David Mundell today?”

Mr Carlaw replied: “Let me be crystal clear: others may be abandoning their posts, but none of us on the Scottish Conservative benches is going anywhere.

“Ruth Davidson and David Mundell have spent the past year fighting for the United Kingdom.

“They are not going to take any lessons from anyone else - not from any carpetbagger who has come late to the defence of the United Kingdom and certainly not from the First Minister.”  

Labour said it was “farcical” that Mr Mundell had given his backing to the draft withdrawal agreement, despite he and Ms Davidson suggesting a “special status” for Northern Ireland which could undermine the Union and boost the cause of Independence was a red line.

Mr Raab cited protection of the Union as his first consideration in leaving the government.

He said: “I believe that the regulatory regime proposed for Northern Ireland presents a very real threat to the integrity of the United Kingdom.”

Quitting as Work and Pensions Secretary, Esther McVey told the PM her plan “threatens the integrity of the United Kingdom, which as a Unionist is a risk I cannot be party to.”

Shailesh Vara also resigned as minister for Northern Ireland with a warning about the “constitutional integrity” of the UK.

He said that pending exit from the proposed temporary customs union - which Brexiters fear with become indefinite - Northern Ireland would be “subject to a different relationship with the EU from the rest of the UK”.

He said: “Whilst I agree there should be no hard border between Northern Ireland and Ireland, the economic and constitutional integrity of the United Kingdom must be respected.”

Suella Braverman quit as Brexit minister - the second holder of the brief to quit.

She said the Irish backstop proposals “set out different regulatory regimes for Northern Ireland and Great Britain threatening to break up our precious Union.

“I am confident - having met with customs professionals in my role at the Department - that this could have been avoided.”

Shadow Scotland Secretary Lesley Laird said: “It is farcical that the Brexit Secretary has resigned because the Prime Minister’s deal undermines the integrity of the UK, while the Scottish Tories stay silent. So much for standing up for Scotland's place in the UK.

“Ruth Davidson and David Mundell threatened to resign if the integrity of the UK was put at risk – and it appears Theresa May has simply ignored them. It’s clear this Tory government is a threat to the future of the UK.

“If David Mundell had a back bone then he would resign with immediate effect.

“We were promised that the Scottish Tories would be a strong block who would work in Scotland’s interests - what an absolute fallacy that has proven to be, they have been outmanoeuvred from the minute they arrived in London.”

On Wednesday night, Mr Mundell said: “I was content to move to the next stage of the process on the basis that Brexit will deliver for our fishing industry – as I and colleagues set out in our letter – and on the basis that arrangements for Northern Ireland will not undermine the economic or constitutional integrity of the UK.”