Britain's Prime Minister Boris Johnson speaks during a debate on Brexit, as parliament sits on a Saturday for the first time since the 1982 Falklands War, in London, Britain October 19, 2019. ©UK Parliament/Jessica Taylor/Handout via REUTERS

LONDON (Reuters) - British lawmakers on Saturday voted for a proposal to withhold support for Prime Minister Boris Johnson’s Brexit deal until formal ratification legislation has passed, a step that will oblige him to ask the European Union for a Brexit delay.

Lawmakers voted 322-306 for the amendment, put forward by former Conservative lawmaker Oliver Letwin. It means that parliament will not vote on Saturday on whether to approve Johnson’s agreement.

Unless Johnson has approved a deal by the end of Saturday, he is obliged by law to ask the EU for a Brexit delay until the end of January 2020. If Johnson can get all the legislation through parliament, he could still deliver Brexit by Oct. 31.