Bracknell MP Phillip Lee confirmed his resignation on Twitter as Johnson addressed the House of Commons and claimed that he was making progress in Brexit talks. Johnson also doubled down on claims that MPs who rail against him to support stopping a no-deal Brexit “destroy” his chances of striking a new deal with Brussels.

Lee’s dramatic defection saw him cross the Commons floor to join his new Lib Dem colleagues on the opposition benches.

 His reasons for resigning lay in his “concern over the approach and direction” of the Conservative party, which he said has been infected with the “twin diseases of populism and English nationalism.”

The move comes just hours before MPs are due to vote on whether to allow opposition lawmakers to seize control of the parliamentary timetable to attempt to pass a law to block the U.K. leaving the EU without a trade deal on October 31, which is Johnson’s “do or die” deadline.

Crucial quote: “The Brexit process has helped to transform this once great party into something more akin to a narrow faction, where an individual’s ‘conservatism’ is measured by how recklessly one wishes to leave the European Union,” Lee said in his resignation letter.

What happens now: Tonight MPs will vote on seizing control of the Commons in order to try and rush through law which will force Johnson to ask for a three-month extension to the Brexit deadline unless a deal is reached by October 19. Time is short because Johnson will suspend, or prorogue, Parliament from September 9, during which time MPs will not sit for around five weeks.

If tonight’s vote doesn’t go in favor of the opposition, Labour leader Jeremy Corbyn could table a vote of no confidence which, if Johnson loses, gives opposition MPs 14 days to form an alternative government, while Johnson could also use this time to persuade his colleagues to allow him to carry on. But if the opposition wins, Number 10 has threatened to call a general election on October 14.

Otherwise, MPs will have to cross their fingers that Johnson can renegotiate a deal with the EU before his “do or die” Halloween deadline, something which the trading bloc has shown unwillingness to do.