Explainer: What happens next after UK PM Johnson loses Brexit vote?

Britain's Prime Minister Boris Johnson speaks at the House of Commons as parliament discusses Brexit, sitting on a Saturday for the first time since the 1982 Falklands War, in London, Britain, October 19, 2019, in this screen grab taken from video. Parliament TV via REUTERS

LONDON (Reuters) - Britain's parliament voted to withhold its approval of Prime Minister Boris Johnson's Brexit deal on Saturday, triggering another law that requires him to request a delay to the country's departure from the European Union.

Johnson has been defiant that he will not negotiate a Brexit delay beyond the scheduled Oct. 31 departure date, saying the law does not "compel me to do so", deepening uncertainty over how and even whether Britain will leave the EU.