LONDON — Jeremy Corbyn will impose a three-line-whip on Labour MPs compelling them to vote to leave the EU, even if the party fails to win a single amendment to the Brexit bill.

A senior Labour source confirmed to Business Insider that MPs will be expected to vote for Theresa May to be given the power to trigger Article 50 — the two-year process by which Britain will leave the EU.

They said that a decision had not yet been taken on the disciplinary process for frontbenchers who defy the whip, saying that "the consequences will be decided after the vote [on third reading] takes place."

Labour are currently seeking to amend the bill before it passes to the House of Lords. The party has already failed to pass amendments boosting parliamentary scrutiny of the Brexit negotiations and are also likely to lose amendments on Tuesday forcing May to hold a 'meaningful vote' on the final Brexit deal.

However, Corbyn has today made clear that the party will vote for the bill regardless.

The decision means that shadow business secretary and key Corbyn ally Clive Lewis will now almost certainly resign from Corbyn's team.

All frontbench Labour MPs would normally have to resign if they defied the three-line-whip. However a spokesperson for Corbyn said last week that while shadow cabinet members would have to stand down, other frontbenchers may be able to keep their job.

Four Labour MPs have already stood down over the bill. However, a number of Labour frontbench MPs, including three of Corbyn's own whips who are in charge of enforcing party discipline, voted against the bill at second reading and have not yet been forced to stand down.

A spokesperson for the party said last week that a decision on their future would be taken after Brexit bill had been passed.

Moral pressure

The Labour leadership believes they must not do anything that would be seen to "frustrate" Brexit. They have therefore decided to give the green light to May's plans.

Asked last year how Labour could have any influence over the Brexit process when they had ruled out voting against it, Shadow Chancellor John McDonnell said they would use "moral pressure" to influence the government.

"I think it's the moral pressure that we'll be able to exert… I don't think it will come down to parliamentary procedures…" he insisted

"No government can resist (the moral pressure)."