Appearing on The Andrew Marr show, Peter Whittle said if Arron Banks, whose fortune is estimated at £100m, withdraws his funding, it will not hurt the party.
"If Arron were to take his money away, there would be other people," he said.
Whittle's comments came after Banks, who has been credited with bankrolling the Vote Leave campaign, launched a stinging attack on leader Paul Nuttall, threatening to plough his cash into a rival political movement unless he is made the party's chairman.
In an interview with The Express, Banks said the party is being run "like a jumble sale", and added Nigel Farage, Ukip's former leader, backs him up.
Banks' comments came after Ukip was handed a humiliating defeat in the Stoke by-election on Thursday after a disastrous campaign by Nuttall, who stood for election in the vote but was beaten by Labour's candidate.
Banks – who in November told Radio 4 he had stopped bankrolling Ukip – said if he is made chairman, he will eject Douglas Carswell, the party's only MP, after allegations Carswell blocked Farage from being given a knighthood (although he has denied it).
“I am giving Paul Nuttall an ultimatum that either I become chairman and sort out Ukip by bringing in business people and professionals to make it electable or I am out of there," he said.
“These dullards [Carswell and Nuttall] aren’t bringing in Tory votes, Stoke proved that. So what are they for? The party now needs to bring in serious people to fix its ramshackle administration, stay relevant and stay radical or it will die.”
Today Whittle admitted Nuttall may have made a mistake in standing in the Stoke by-election.
"Paul shouldn't have run so early. He'd only been leader for 12 weeks. People hadn't got to know him."
However, he added: "There are many by-elections coming up."