Labour and the Conservatives are neck and neck in the byelection battle for Nadine Dorries' old constituency of Mid Bedfordshire, new polling has revealed.
The survey suggests that a split in the 'progressive' vote could allow Rishi Sunak's party to hold the seat despite greater unpopularity.
The campaigners are trying to create a unofficial electoral pact so only one of the major parties wants to take the blue wall stronghold.
The Labour Together poll, which puts Labour and the Tories on 29 per cent, will add pressure on Ed Davey to accept that Keir Starmer's party has the best chance of overturing a 24,000 Tory majority.
The Lib Dems are in third place on 22 percent in the contest, set to take place on October 19th. Reform UK is 7 per cent, while independent candidate Gareth Mackey has 6 per cent.
The Survation also found that a significant percentage of people in the seat who are planning to vote remain undecided, with Labour activists pouncing upon the results to encourage Lib Dem supporters to switch to Sir Keir's party.
The polls 'clearly shows this is a two-horse race between Labour and the Conservatives', said Josh Simons, the director of Labour Together.
The polls have shown that Labour has lost its advantage in the polls. In June, a poll by the centre-right party polled Labour at 28 per cent, the Tories at 24 per cent and the Lib Dems at 15 per cent.
Prof Curtice has said polling gurus could 'collapse', but they could still 'hang on' because of an almost even vote split between Labour and the Lib Dems.
Tory peer and elections expert Robert Hayward also said Rishi Sunak's party had a good chance of winning. ''s determination to prove he can appeal to all parts of the country has surprised the Lib Dems,'' he told The Independent.
The Compass campaign group has warned that the 'ghost' of the recent Uxbridge by-election should loom large over Mid Bedfordshire - pointing to the Tories hanging on despite Boris Johnson's unpopularity.
The Lib Dems have argued that there's a natural ceiling to the Labour vote in Mid Bedfordshire because of the demographics in the rural constituency.
Mr Davey made his fifth visit to the home counties seat on Saturday, where he will speak to voters in rural villages. Lifelong Conservative voters are turning to the Liberal Democrats to send this government a message, he said.
The Prime Minister has formally resigned earlier this month having pledged to leave the government early June over her failure to gain a peerage in Boris Johnson's resignation honours list.
The arch Johnson loyalist had been furious at not winning a peerage in her former boss' resignation honours - alleging that 'posh boy' Mr Sunak had blocked it.
The ex-culture secretary has claimed that No 10 is 'pushing a line' that her delayed book launch is because she has broken the ministerial code and has been silenced.
The book, The Plot: The PoliticalAssassination of Boris Johnson, had been scheduled for release in September to coincide with the start of the Tory party. It also announced a delay for legal checks until November.
Mr Dorries denied the book had been delayed because of ministerial code issues. It's not about me or my time in office, it's all about them.