Photo taken on Oct. 19, 2019 shows the Houses of Parliament in London, Britain.(Xinhua/Han Yan)

The decision does not mean that Johnson's deal has failed, but it will make it difficult for him to stick to his deadline of ending Britain's membership of the EU on Oct. 31.

LONDON, Oct. 19 (Xinhua) -- British lawmakers on Saturday voted for a key amendment to force British Prime Minister Boris Johnson to seek another Brexit extension from the European Union (EU).

By 322 to 306, MPs supported an amendment put forward by former Conservative MP Oliver Letwin that will withhold parliamentary approval for Johnson's deal until parliament passes the EU withdrawal bill legislation.

Photo taken on Oct. 19, 2019 shows the European Union flag and the Union Jack flag outside the Houses of Parliament in London, Britain.(Xinhua/Han Yan)

The decision does not mean that Johnson's deal has failed, but it will make it difficult for him to stick to his deadline of ending Britain's membership of the EU on Oct. 31.

The decision brought what was expected to be a lengthy debate to a crashing end.

Johnson announced after the result was announced that he will present legislation next week in the House of Commons, with the intention of Britain leaving the EU at the end of the month.

British Prime Minister Boris Johnson leaves 10 Downing Street for the House of Commons in London, Britain, Oct. 19, 2019.(Xinhua/Han Yan)

He told MPs he will not negotiate a delay with the EU, adding that the law does not compel him to do so.

Under a law passed by the House of Commons, Johnson is required to write to Brussels by tonight seeking an extension of Britain's membership of the EU.

MPs asked Speaker John Bercow whether the prime minister is required to comply with the law. Bercow said the Commons will have to await developments.

Jacob Rees-Mogg, the Leader of the House of Commons, told MPs that a debate on EU legislation will be held in the Commons on Monday.

Downing Street refused to say whether Johnson would write to Brussels asking for the extension, the Daily Telegraph reported.

People react to the latest result of the amendment during the "Together for the Final Say" event at the Parliament Square outside the Houses of Parliament in London, Britain, Oct. 19, 2019.(Xinhua/Han Yan)

Opponents of Johnson's deal celebrated the decision, but Letwin told MPs he will vote for the deal with the intention that Britain leaves the EU on Oct. 31, adding he could now do so with the knowledge that if the Brexit bill does not pass in time Britain will not crash out of the bloc without a deal.■