Boris Johnson has rejected the suggestion from Nigel Farage and Donald Trump that he should work with the Brexit Party during the election.
The Tory leader told the BBC he is “always grateful for advice” but he would not enter into election pacts.
His comments come after the US president said Mr Farage and Mr Johnson would be “an unstoppable force”.
Downing Street sources say there are no circumstances in which the Tories would work with the Brexit Party.
In an interview with BBC political editor Laura Kuenssberg, the prime minister said the “difficulty” of doing deals with “any other party” is that it “simply risks putting Jeremy Corbyn into Number 10”.
“The problem with that is that his (Mr Corbyn’s) plan for Brexit is basically yet more dither and delay,” Mr Johnson said.
When pushed on whether he would rule out a deal with Mr Farage, Mr Johnson replied: “I want to be very, very clear that voting for any other party than this government, this Conservative government… is basically tantamount to putting Jeremy Corbyn in.”
The UK is going to the polls on 12 December following a further delay to the UK’s departure from the EU, to 31 January 2020.
The BBC will be talking to other party leaders during the course of the campaign.
US president Donald Trump told Nigel Farage’s LBC show on Thursday that the Brexit Party leader should team up with Mr Johnson to do “something terrific” and he also criticised the PM’s EU withdrawal agreement.
Meanwhile, Mr Farage has called on the prime minister to drop his Brexit deal, unite in a “Leave alliance” or face a Brexit Party candidate in every seat in the election.
Mr Johnson said there were “lots of reasons” why he thinks a Labour government would be a “disaster”, but he believed a Labour government would see a renegotiation with Brussels on a Brexit deal, then another referendum.
“Why go through that nightmare again?” He said.
The prime minister also suggested that the US president was wrong to believe that a trade deal would be impossible with the UK after Brexit.
Mr Johnson said his “proper Brexit” deal “enables us to do proper all-singing, all-dancing free trade deals”.
“It delivers exactly what we wanted, what I wanted, what I campaigned in 2016 to come out the European Union,” Mr Johnson said.
When asked about the criticism from Mr Trump, Mr Johnson said: “I am always grateful for advice from wherever it comes and we have great relations as you know with the US and many many other countries.
“But on the technicalities of the deal anybody who looks at it can see that the UK has full control.”
Mr Johnson said he hoped the government could get Brexit “over the line” by the middle of January if he wins a majority, claiming that the current Parliament would never have passed his Brexit deal.
“Their strategy was to keep rope-a-dopeing the government” to push the date back and back, he said, before adding: “It would have been totally miserable”.
He said he was left with “no choice” but to call a general election, saying: “Nobody wants an election but we’ve got to do it now.
“This is a Parliament that is basically full of MPs who voted Remain.
“They voted Remain and they will continue to block Brexit if they’re given the chance – we need a new mandate, we need to refresh our Parliament.”
Mr Johnson also said there was no question that the NHS would be part of any future trade negotiation, but he did not rule out expanding the amount of private provision in the health service in the future.
“Of course there are dentists and optometrists and so on who are providers to the NHS, of course, that’s how it works,” he said.
“But… I believe passionately in an NHS free at the point of use for everybody in this country.”