London – British Prime Minister Boris Johnson sent a letter to the European Union to formally request a delay for Brexit after Parliament forced his hand — but the letter didn't have his signature. He then sent another letter with his signature saying he thought a delay would be a mistake, BBC News reports.

EU Council President Donald Tusk tweeted that he had received the extension request.

Tusk did not provide details of its content but added that he will now consult EU leaders "on how to react."

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Members of Britain's Parliament passed an amendment Saturday that seemingly forced Johnson to ask the EU for a Brexit extension past the current October 31 deadline. Under U.K. law, Johnson is required to either get his deal approved today or seek an extension from the European Union to that end-of-October date, but Johnson vowed to forge ahead.

"I will not negotiate a delay, nor does the law force me to," Johnson said after the result of the vote was announced, adding that he would be putting his Brexit deal up for a vote next week.

It was unclear how he planned to get around the law.

Saturday's session of Parliament was only the fifth time lawmakers have met on a Saturday since the start of World War II.

The "Letwin amendment"

Some lawmakers are worried that if Johnson's deal passes, the legislation to actually implement it might not be ready by October 31, the date the U.K. would be scheduled to leave the EU. They say there is a possibility the U.K. could be forced, therefore, to exit the European Union "on no-deal terms."

Oliver Letwin, a lawmaker behind the amendment and for whom it is named, said it would — if passed — make sure Britain does not leave the EU at the end of the month, "by mistake if something goes wrong during the passage of the implementing legislation."

"If they wish to avoid a no-deal outcome, the single best thing they could do is vote for this deal tonight," Johnson told lawmakers during debates in the House of Commons on Saturday.

Meanwhile, thousands of people gathered in central London to demand a second public referendum on whether Britain should remain in the European Union.

"I'm here because the only democratic way forward is to ask the British people in a confirmatory referendum: Is this what you really want?" 17-year-old Leo Buckley, who was taking part in the march, told CBS News.

"As a citizen of Europe and a citizen of the future, I would like to stay in the EU," he said.

"I am so against this Brexit business. I'm old enough. I'm 82," Lynne Hall told CBS News. "I've seen what nationalism does."