The Conservative Party has reportedly had an electoral pact deal with the Brexit Party turned down by Nigel Farage.
According to the Daily Telegraph, the Tories proposed a deal which would mean the Brexit Party target just 40 key seats.
Mr Farage has withdrawn candidates from seats won by the Conservatives at the last general election, but pledged to stand in every seat won by Labour.
Candidates who want to stand as MPs need to hand in nomination papers by 4pm on Thursday - which effectively acts as a deadline if any deals are to be agreed.
The Brexit Party leader insisted on Thursday that his party would continue to stand in Labour-held seats, ITV News Correspondent Emma Murphy reports.
However critics claim that Mr Farage's move could scupper the Conservatives' chance of a majority.
The Daily Telegraph reported that the deal was turned down by the Brexit Party leader, who urged the Tories to give the Brexit Party a clear run in Labour-held seats where the Conservatives can "never win".
A Tory source said: "We don’t do electoral pacts as we have been very clear on.”
A Brexit Party source said: “At every election the Tories have upwards of 100 paper candidates.
“If this offer was made it was an offer of the status quo, in in other words, no offer at all.
“It looks like an attempt to portray the Brexit Party and Nigel Farage as unreasonable, despite the huge concessions that we have made, both on a policy and on the unilateral decision not to stand in the 317 Tory held seats.
“If the Tories are serious then this isn’t the way to show it.”
The prime minister has repeatedly claimed that voting Conservative is the "only way" to get Brexit done, while Business Secretary Andrea Leadsom warned that voting for Mr Farage’s party hands the keys of Number 10 to Jeremy Corbyn.
Mr Farage's party has already announced it would not run in 317 constitutions which were won by the Conservatives in 2017, after initially saying his party would field more than 600 candidates.
He said he made the decision amid fears that it could split the Brexit vote, leading to a hung parliament and a second referendum.
But there have been calls for Mr Farage to go even further if he wants to keep Mr Corbyn out of Number 10.
Baroness Brinton, president of the Lib Dems, said her party is “absolutely clear” that it is “fighting for Remain”, adding: “David has not quite got to a Remain position.”
She told BBC’s Newsnight: “If he really wants to lend his vote to the Liberal Democrats then he could stand back in South West Hertfordshire.
“Appreciate that he doesn’t want to do that, but we wish to stand in South West Hertfordshire.”
Baroness Brinton added: “We will fight it for everything.”
Elsewhere, European Council president Donald Tusk has appeared to back Mr Johnson’s opponents by advising campaigners not to give up on stopping Brexit.
In a speech, Mr Tusk said: “The UK election takes place in one month. Can things still be turned around? Hannah Arendt taught that things become irreversible only when people start to think so.
“So the only words that come to my mind today are simply: Don’t give up. In this match, we had added time, we are already in extra time, perhaps it will even go to penalties?”
His remarks came as Ms Leadsom said she is “absolutely confident” that the Conservatives will get a free trade deal done by the end of 2020.
But when pressed on the matter on ITV’s Peston, Ms Leadsom said: “Until we reach the end of 2020, we won’t know for sure.”
She added: “I think anybody who wants to leave the European Union with a deal needs to vote Conservative.
“Voting for the Brexit Party won’t mean we leave the EU. It will simply mean we get Jeremy Corbyn.”
ITV News has approached the Conservative Party for comment.