Nigel Farage has urged the Tories to stand aside for his Brexit Party in seats they have no prospect of taking from Labour.
In a major climbdown, Mr Farage announced on Monday that his party would not run in the 317 constituencies the Conservatives won at the 2017 general election.
He is now urging the Tories to reciprocate by giving the Brexit Party a clear run in Labour-held seats where they can "never win".
"I've just gifted the Conservative Party nearly two dozen seats and I did it because I believe in Leave," he told BBC Breakfast.
"Now, if they believed in Leave, what they would do is stand aside in some seats in Labour areas where the Conservative Party has not won for 100 years and will never win.
"I think what you're seeing from this reaction is, for the Conservative Party, it is about them as a party, not about delivering Brexit."
His appeal came as senior Tories urged him to go even further and withdraw from key Labour marginals which Prime Minister Boris Johnson needs to take if he is to secure a Commons majority in the election on December 12.
Mr Farage said on Monday that he took the "difficult decision" to stand candidates down, amid fears that it could split the Brexit vote, leading to a hung parliament and a second referendum.
However, former Conservative leader Iain Duncan Smith said Mr Farage needed to go even further if he wanted to keep Jeremy Corbyn out of Number 10.
"It's a good start, but if they want to deliver Brexit they've still got to focus on the fact that if they divide the vote they'll let Labour in," he told The Sun.
"He's going to have to go further. This is a game of two halves - we've had the first half and now we're going to have the second half.
"The second half is where he gets to decide which seats he stands down from, and he's going to have to stand down from some of them."
Mr Farage's decision to pull his candidates came amid reports of secret talks between the Brexit Party leader and the pro-Leave Tory European Research Group.
They were said to have resulted in Mr Johnson issuing a video over the weekend in which he promised that he would not extend the planned Brexit transition period beyond the end of 2020 and that he would negotiate a Canada-style free trade deal with the EU.
Mr Farage said that the comments represented a significant shift in the Government's position, giving him hope that it would deliver a true Brexit.
In a further twist, he claimed he had been offered a peerage as recently as last Friday in an attempt to bring him on board.
Labour leader Jeremy Corbyn said a Boris Johnson and Nigel Farage-led government would "threaten all of our regulations" and result in a deal with US President Donald Trump.
Speaking on the campaign trail in Blackpool yesterday, Mr Corbyn said: "I think what we have before us is an alliance which is Donald Trump and Nigel Farage and Boris Johnson.
"We know where that alliance is designed to take us - into a sweetheart trade deal with the United States that will threaten all of our regulations, all of our conditions and threaten our public services."
Mr Corbyn added: "Farage and Johnson only offer division, division, division and a deal with Donald Trump."
He added that his party "will have none of it".
Liberal Democrat Brexit spokesman Tom Brake said: "These talks show that Nigel Farage is pulling the strings behind the scenes. He is the puppet master in Boris Johnson's Brexit horror show.
"Every vote for the Conservatives is a vote for an extreme Brexit agenda backed by Nigel Farage," he added.