Femi Oluwole has said leaving the European Union without a deal would be "incredibly undemocratic" and in "direct violation" of the voters' will.
The remain supporter told talkRADIO’s Dan Wootton the 2017 election showed most Britons do not want a no-deal Brexit.
“In 2016 52 per cent voted to leave the EU. But did they say what relationship we’d end up having with the EU?” he said.
“In 2017 - the only opportunity the British people have had to say what relationship we want to have with the EU post-Brexit - 54 per cent of voters voted for parties whose manifestos explicitly ruled out no deal. That is the majority will of this country.”
He added: “So for Parliament to take us out of the EU without a deal would be to go in direct violation of the majority of those who put it in place.”
Mr Oluwole’s views have been disputed by Guido Fawkes journalist Tom Harwood, who told talkRADIO no deal is “not the end of the world”.
“In fact it could be the impetus to making us one of the most dynamic, wealthy, creation hubs of the world,” he said.
Mr Oluwole has urged Labour to push for a vote on the final Brexit deal, calling it the “most democratic way of doing Brexit”.
“What Labour should be doing now, and should have been doing for the past eight months to be honest, is campaigning for a public vote,” he said.
“If we lose, if people vote for that deal I accept that because there will actually be democratic consent for that deal. In fact that’s the most democratic way of doing Brexit.”
However Mr Harwood said Labour is guilty of “confusing ridiculous behaviour designed to confuse the voters”.
“They’re still trying to have their cake and eat it,” he said.
“They’re saying that while there’s a Tory government they’ll push for a second referendum, but that if they went into government they would push for some kind of mythical Labour deal”.