Liberal Democrat leader Sir Vince Cable has accused Jeremy Corbyn of acting in "collusion" with the Conservatives to enable Brexit to happen.
In an interview with BBC1's The Andrew Marr Show, Sir Vince said there was a "simmering anger" in the Labour ranks at their leader's failure to oppose Britain's withdrawal from the EU.
He predicted Mr Corbyn would be forced to back a second referendum on the final Brexit deal with Brussels - and he said Britain's withdrawal from the EU was not inevitable.
"Jeremy Corbyn is crucial to this. The vast majority of his MPs and his party and his supporters are very concerned about the fact that he hasn't opposed Brexit," he said..
"He has effectively worked in collusion with Theresa May and her Government to enable Brexit to happen. I think there is a simmering anger about that.
"I think as we get through this year and we get closer to the final decision, and it becomes clear that we are going to get a very bad deal from these negotiations, he will be under enormous pressure to support a referendum on the final deal.
"I think the Labour Party will come round to it as will as significant number of dissident Conservatives."
Sir Vince said that he believed that Brexit could still be stopped.
"I don't accept that it is inevitable. The probability is that it will happen, but there is a significant possibility that it won't it," he said.