Labour has opened up its biggest poll lead since the election - sparking warnings that backing the PM's controversial Brexit plan will install Jeremy Corbyn in No10.

Support for the Conservatives has fallen sharply after the party have been gripped by chaos over its Brexit plans.

Theresa May unveiled her controversial Chequers blueprint a week ago - sparking the shock resignations of Boris Johnson and David Davis and Boris Johnson.

It plunged the Government into turmoil and left Mrs May battling for her political survival amid a mutiny from her MPs, who are threatening to topple her if she does not ditch the plan.

An Opinium poll for The Observer newspaper found that Tory support has plummeted to 36 per cent - some six points lower than it was in June.

An Opinium poll for The Observer newspaper found that Tory support has plummeted to 36 per cent - some six points lower than it was in June.

Meanwhile, Labour have stayed on 40 per cent, while Ukip - the Brexit backing party most commentators had written off - have surged to 8 per cent.

Steve Baker, the ex Brexit minister who followed his boss Mr Davis and quit in fury at the proposals, said the poll shows that backing Chequers would effectively hand the keys to No10 to Mr Corbyn.

He said: 'It looks like Chequers means Corbyn. But it doesn't have to be this way. There's still time to change course. Just.'

The poll also shows that Mrs May's personal ratings have nosedived - pluging from -8 to -24.

It comes at the end of a hugely turbulent week for the PM, who has seen her Brexit plans savaged by her own MPs and Donald Trump.

The US President risked sending the Special Relationship into meltdown by warning that the Chequers plan kills off any hope for a transatlantic trade deal.

And he also heaped praise on his 'friend' Mr Johnson - saying he would make a great Prime Minister.

His undiplomatic remarks hit newsstands as he was given the red carpet treatment by the British Government as he made his hugely controversial visit.

Today, the PM has warned Tory rebels seeking to wreck her blueprint to leave the EU they could be left with 'no Brexit at all' unless they fall into line.

The Prime Minister said threatened revolts by her mutinous MPs risked undermining any chances of a deal with Brussels.

In an article for The Mail on Sunday, she called for MPs to take a 'practical and pragmatic' approach rather than face a 'damaging and disorderly' Brexit.

She said: 'We need to keep our eyes on the prize. If we don't, we risk ending up with no Brexit at all,' she said.

Theresa May (pictured left with Donald Trump at Chequers on Friday) has seen her ratings tumble after a turbulent week in which her Brexit blueprint triggered resignations and was savaged by the US President. Meanwhile, Labour have remained stead on 40 per cent

Steve Baker, who quit as a Brexit minister in fury at the Chequers plan - has warned that backing will hand the keys of No10 to Jeremy Corbyn

'I know there are some who have concerns about the 'common rule book' for goods and the customs arrangements which we have proposed will underpin the new UK-EU free trade area. I understand those concerns.

'But the legacy of Brexit cannot be a hard border between Northern Ireland and Ireland that unpicks the historic Belfast Agreement.

'It cannot be the breaking up of our precious United Kingdom with a border down the Irish Sea. And it cannot be the destruction of integrated supply chains and just-in-time processes on which jobs and livelihoods depend.'

But she is facing stiff criticism from her MPs with Jacob Rees-Mogg - defacto leader of the Brexiteers - warning there had been an attempt to 'gull Brexiteers'.

The damning verdict from the head of the European Research Group of Leave-supporting MPs is likely to fuel speculation the PM could face a challenge to her leadership.