His warning comes after Mr Farage earlier this week staged a climbdown from his vow to fight 600 seats in the general election by promising to give 317 sitting Conservative MPs a free ride. But Mr Farage was told to "go further".
Mr Banks said: "There are 48 hours to save Brexit and save the country from a Corbyn government... Nigel has remade the Conservative Party in his own image, the Conservative Party is the Brexit Party."
He added: "The only way Brexit is going to get delivered is by a Boris majority."
The deadline for candidate nominations for the December 12 poll is Thursday.
Mr Farage is facing a furious backlash from Brexit Party candidates as one accused him of dropping candidates "like a stone".
He announced on Monday that the party would not stand in 317 Tory-held seats after Boris Johnson flatly refused to buckle to pressure for an election pact.
Robert Wheal, who was due to stand for the Brexit Party in Arundel and South Downs, said Leave supporters could "kiss goodbye" to Brexit following the decision and vowed to spoil his ballot paper.
Speaking to LBC, Mr Wheal told presenter Nick Ferrari: "Half the Brexit supporters have worked their socks off for that party and he has dropped them like a stone at 12 o'clock yesterday."
It comes as Mr Farage called on the Tories to stand aside in Labour-held seats, telling BBC Breakfast: "I've just gifted the Conservative Party nearly two dozen seats and I did it because I believe in Leave."
Prime Minister Mr Johnson earlier rejected Mr Farage’s demand. “We are going to run in all seats,” ruled a source close to the Tory leader. “We are not going to be standing down candidates anywhere.”
But Mr Wheal criticised Mr Farage’s move, saying that the Conservative Party was only offering "Brexit in name-only."
He said: "It was made very clear to us all at the first Brexit Party rally that we will put country before party and that if Farage managed to do a deal with
Boris Johnson that he would agree to drop his rotten WA Agreement and take on a no-deal that we would all stand down and support him.
"But what we have here is absolute codswallop. Farage hasn't even got a deal.”