Reform leader Richard Tice dismissed claims his party is hoping to do a deal with Boris Johnson.
Allies of the ex-PM and Nigel Farage were said to have been in contact to discuss a realignment of the right after the general election.
But Ms Tice said Mr Johnson was “obsessed” with green targets and putting up taxes, which would put him directly at odds with Reform’s plan.
Asked about talks between the two men, Mr Tice said: “I don’t know but I very much doubt it. If you look at what Boris stands for politically and what we stand for actually, they are quite a long way apart.
“Boris is for raising taxes, he is for higher government spending, he’s obsessed with net zero.
Mr Tice told Times Radio: “That’s the opposite of what we are trying to do. We are trying to create growth in the country by reducing taxes and reducing wasteful spending.”
It followed a report in a Sunday newspaper that suggested Mr Farage would fight to win Clacton in Essex for Reform with Mr Johnson returning to parliament at a by-election.
The ex-PM would then “woo” Mr Farage to persuade him to return to the Tories.
A spokesman for Mr Johnson said: “Boris Johnson’s number one priority is campaigning for Ukrainian victory and lasting peace. He is focused on that. He is also writing a book and speaking.”
A spokesman for Mr Farage said the claims were “desperate”.
