LONDON, United Kingdom (AFP) — Prime Minister Boris Johnson on Tuesday lost his working majority in parliament ahead of a showdown with rebel MPs over Brexit that could lead to a snap election within weeks.

Johnson condemned a plan by lawmakers to block his Brexit strategy as “surrender” and said it would undermine his intention to negotiate a new divorce deal with the EU.

He said the move by opposition MPs and members of his Conservative party to try to delay Brexit beyond October 31 if he cannot agree exit terms with Brussels was like “running up the white flag”.

Ahead of a first vote in the House of Commons on Tuesday evening, Johnson said: “There are no circumstances in which I will ever accept anything like it”.

His aides had already warned that defeat would force him to call a snap election ahead of a crucial EU summit on October 17-18 — and a mere fortnight before Brexit.

The rebels believe they have the numbers to force through the plan, which is backed by the main opposition Labour party and could delay Brexit to January 31.

In a theatrical show of defiance, Conservative MP Phillip Lee crossed the floor of the Commons while Johnson was making his statement, to defect to the pro-European Liberal Democrats.

As a result, the prime minister no longer has a majority in the 650-seat chamber — but the defection does not automatically bring down the government.

This can only happen if the government loses a formal confidence vote.

On a day of high drama, an Edinburgh court meanwhile heard a legal challenge against Johnson’s decision to suspend parliament next week for more than a month, which critics said was a bid to silence MPs.

The heightened political tension sent the British pound tumbling on Tuesday to its lowest level against the dollar in almost three years.