BOTH Labour and the Liberal Democrats have set their sights on winning the by-election caused by the resignation of Nadine Dorries, potentially offering the Tories a lifeline.

Despite the possibility of a split in the anti-Tory vote, Labour ruled out any "deals" with other parties to minimise the chances of the Tories holding on.

The former culture secretary finally quit as the MP for Mid Bedfordshire on Saturday, 11 weeks after saying she was leaving with “immediate effect” after being denied a peerage.

She departed with a brutal broadside against Rishi Sunak, saying he had no mandate to be Prime Minister, no achievements and was responsible for a “zombie parliament”.

Her exit means there is likely to be a by-election in the seat in October.

In 2019, Ms Tories had a 24,664-vote majority over Labour, who had 14,028 votes, with the Liberal Democrats a distant third on 8,171.

However UK Liberal Democrat leader Sir Ed Davey today said his party was “increasingly confident” it had a “really good chance” of winning the  seat.

The LibDems flipped a 19,000-vote Tory majority in Somerton and Frome in July from second place and a 24,000-vote lead in Tiverton & Honiton from third place last year.

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Sir Ed told BBC Breakfast on Sunday: “It’s clear that the people of Mid Bedfordshire feel the Conservative Party is out of trust and they see the Liberal Democrats as the main challenger.”

“It’s really clear – the evidence is overwhelming – that in seats like Mid Bedfordshire it’s the Liberal Democrats who are the only ones who can beat the Conservatives.”

But Labour also said it was best placed to gain Mid Bedfordshire, setting up a clash with the LibDems that could split the anti-Tory vote.

Labour’s Mid Bedfordshire campaign lead Peter Kyle told Sky News: “We are actually in a great position to win this seat in what would be an historic by-election victory.”

The shadow Northern Ireland secretary said Mid Bedfordshire was a “bigger challenge” for Labour than Selby & Ainsty in Yorkshire, where it overturned a 20,000 Conservative majority in a by-election in July, but added “it’s one that we are actually prepared for”.

Labour chairwoman Anneliese Dodds admitted it would “take an absolutely enormous change” for Labour to win, but insisted her party was in "pole position" for the seat.

She said: “I think it really is all to play for for Labour with this by-election. They desperately need an MP who will be focused on them full-time."

She added that "Labour won't be cooking up any deals".

Ms Dorries, who is expected to leave her parliamentary seat on Tuesday, had been under mounting pressure to quit, including from fellow Tory MPs.

Chancellor Jeremy Hunt is due to aid her exit from the House of Commons by appointing her Steward and Bailiff of the Three Hundreds of Chiltern on the first working day after the bank holiday, meaning she is an MP no more.

Despite Ms Dorries’s hugh majority in 2019, the Tories face a challenge holding the seat, after a run of by-election losses across England, because of the controversy over her belated departure and work rate.

She has not spoken in the Commons for more than a year or voted since April, yet was keeping up lucrative second jobs as a TV host and newspaper columnist, earning her the nickname “Dosser Dorries”.

A Boris Johnson loyalist, she said she was staying an MP until she was told why she was denied a peerage in Mr Johnson’s resignation honours list.

In her resignation letter, the former nurse accused Mr Sunak of demeaning his office and risking her safety by whipping up “a public frenzy” against her.

In a 1,700-word statement she told him: "Since you took office a year ago, the country is run by a zombie Parliament where nothing meaningful has happened.

"You have no mandate from the people and the government is adrift. You have squandered the goodwill of the nation, for what?"

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She continued: "It is a fact that there is no affection for Keir Starmer out on the doorstep.

“He does not have the winning X factor qualities of a Thatcher, Blair or a Boris Johnson, and sadly, prime minister, neither do you."

Veterans minister Johnny Mercer said voters were not interested in the criticism. 

He said: “I think people are tired of raking over the coals of the Boris Johnson government.

Senior Tory Caroline Nokes told BBC Radio 4: "I am not planning on wasting a second more of my life thinking about Nadine Dorries.

"Nadine has turned her resignation into a psychodrama and sadly this seems more about gathering column inches for Nadine rather than a Conservative Party she claimed to be a loyal member of a few weeks ago."