Three MEPs are quitting the Brexit Party and urging people to back the Conservatives at the upcoming election.
Annunziata Rees-Mogg – sister of cabinet minister Jacob – as well as Lance Forman and Lucy Harris are due to announce their decision later today.
They will urge voters to support the Tories on polling day in exactly one week's time to "get Brexit done".
Ms Rees-Mogg, MEP for the East Midlands and an ex-Conservative candidate, said: "We need a strong Leave-supporting government to deliver the Brexit 17.4 million voted for.
"The Conservatives are the only option for Brexit supporters and democrats alike."
Nigel Farage, leader of the Brexit Party, said he was "disappointed" at the news.
He claimed that after he stood down candidates in all Tory-held seats and called on Boris Johnson to reciprocate in other areas, the MEPs' decision would only split the Leave vote in Labour heartlands.
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"We are disappointed that four of our MEPs don't seem to understand that we both saved the Conservative party from large scale losses to the Liberal Democrats in the South and South West of England," Mr Farage said.
"We are also hammering the Labour Leave vote in its traditional heartlands making it much easier for the Conservatives to win many of those seats.
"The only vote on the Leave side that is currently being split is in areas such as Barnsley, the South Wales valleys, Doncaster and Hartlepool where there is a risk that the Tories will split our vote."