NICOLA Sturgeon has urged the Conservatives to “get a grip” after Tory colleagues used denigrating language to threaten Theresa May’s leadership.

As the pressures of Brexit mount, the Prime Minister is facing increasingly shrill siren voices about a possible attempt to oust her.

One backbencher said Mrs May was entering the “killing zone” and that “assassination is in the air”.

One unnamed former minister noted: “The moment is coming when the knife gets heated, stuck in her front and twisted. She’ll be dead soon.”

Those Tory MPs plotting her political downfall are calling on their party leader to attend this Wednesday’s meeting of the backbench 1922 Committee, describing it as a “show trial” with one MP warning that the PM should “bring her own noose”.

The First Minister hit out at the use of such language, tweeting: “Few disagree with her more than I do but language like this debases politics. Get a grip, Tories.”

Theresa Villiers, the former Northern Ireland Secretary, also expressed concern, saying the comments about the PM were "disturbing".

The Brexiteer stressed: “It's really unhelpful. We have got to trust the Prime Minister to do the job on the negotiations. I don't think a leadership election would be remotely helpful at this stage and it's important for this kind of speculation to stop."

Her Tory colleague Robert Halfon also condemned the use of derogatory language, telling Sky’s Ridge on Sunday: “I say to the people giving those quotes: this is not the way to change things.

"This just confirms what many of the public think of us; that we are all potentially out for ourselves and not on the side of working people."

The former minister added: "Who is this magic king or queen over the water that is suddenly going to solve all the Conservative Party's problems?

"It doesn't matter if it is Theresa May or Mother Theresa, unless we get our values right, unless are seen by the public that we are on their side, unless we sort out Brexit and it unifies the party, it doesn't matter who's leader."

The PM’s Conservative critics say they are near to getting the 48 signatures needed to spark a confidence vote in Mrs May but 159 votes would then be needed to automatically trigger a leadership contest. Moreover, if she won, the PM could not be challenged again for another year.

Dominic Raab, the Brexit Secretary, said as the Brexit talks neared the end, it was understandable there were “jitters on all sides of this debate”.

But he urged the party to “hold our nerve” and wait and see what the final deal would look like, promising MPs that they would have “their full say over it".

Mr Raab added: "Now is the time to play for the team."