Frank Field has claimed the Liberal Democrats "are finished" if Boris Johnson's Brexit deal gets through Parliament.
The Independent MP slated the party for pledging to stop Brexit, claiming it is their "one policy".
"They have put everything around one policy, that they will oppose the decision of the British people at the last referendum," he told talkRADIO's Julia Hartley-Brewer.
"If we get a deal through, a party that has concentrated everything on saying it wants to go back on what the British people came to a decision on... I don't think it is going to stand much of a chance at a general election."
Mr Field said he will be backing the new deal in a vote on Saturday, which will be the first weekend Commons sitting in 37 years.
"We promised that we would see the decision [referendum outcome] through, and on Saturday we have a serious chance of fulfilling that pledge to the electorate," he added.
The Work and Pensions Select Committee chair also took a swing at the Labour Party, who have insisted they will not the support the deal, instead calling for a second referendum.
"You’ve really got to have something wrong with your head to think the solution to this is to have a second referendum," he continued.
"The idea that we should prolong this agony I think is sheer madness.
"I would have thought we found it so difficult to implement the decision of the first referendum, and to think that we're now going to plunge the country into a second referendum? I think the country would be very displeased."