Mr Farage has quit and returned once before, in the space of a few days, following the 2015 General Election.
"If Brexit wasn't delivered, then I would have to think seriously about plunging back in," he said. "But I hope I don't have to."
Meanwhile, he revealed he felt sorry for David Cameron when he was forced to resign as prime minister after the referendum but was less sympathetic towards ex-chancellor George Osborne.
"I'd have dragged him out by the scruff of the neck," he said.
"I thought his behaviour was despicable.
"Pasty-faced b****rd. I'm pleased to see the back of him. I hope he never ever appears in public again."
