"Hillary says that you have to have a campaign that appeals to the struggling, the striving and the successful," Mr Clinton said. "We have to do this together. And Bernie says just go get the money from the millionaires."

Tim Farron, the Liberal Democrat leader, said: "The idea that Bill Clinton thinks that Jeremy Corbyn is useless should come as no surprise to anybody. But it shows you how far into the wilderness Labour have gone. Labour are the most irrelevant the party has ever been."

The speech by Mr Clinton emerged as Americans prepared to head to the polls to elect either Mrs Clinton or her rival Donald Trump to the White House.