Britain's Prime Minister Boris Johnson speaks to lawmakers inside the House of Commons to update details of his new Brexit deal with EU, in London Saturday Oct. 19, 2019. At a rare weekend sitting of Parliament, Johnson implored legislators to ratify the Brexit deal he struck this week with the other 27 EU leaders. Secretary of State for Exiting the European Union, Stephen Barclay, left, and Business Secretary Andrea Leadsom, right. (Jessica Taylor/House of Commons via AP)

LONDON (AP) — British Prime Minister Boris Johnson is pressing ahead to try to win parliamentary backing for his new Brexit deal as the European Union considers his grudging request to extend the looming Oct. 31 Brexit deadline.

Johnson late Saturday sent an unsigned letter to the EU seeking a delay to Britain's impending departure from the bloc, as required by law. But he followed it with a signed letter indicating that he does not favor another extension.

EU officials have not responded to the request.

Johnson could face legal challenges from opponents who feel that sending the second letter was done to frustrate Parliament, which has not approved his Brexit plan but does want to avoid a no-deal Brexit.

Johnson returns to Parliament on Monday to keep seeking support for his Brexit proposal, which was approved Thursday by EU leaders.

In this image issued by 10 Downing Street, showing of a letter written by British Prime Minister Boris Johnson addressed to the European Council President Donald Tusk asking the European Union for a delay to Brexit Saturday Oct. 19, 2019. The British government has formally asked the European Union for a delay to Brexit — but also sent a letter from Prime Minister Boris Johnson arguing against it. Johnson was forced to request a delay after Parliament voted to delay a decision on whether to back his Brexit deal. A law passed last month compelled the government to try to postpone Britain's departure if no deal was agreed by Saturday. (Downing Street via AP)
Labour Party leader Jeremy Corbyn delivers a speech at the Grand Central Hall in Liverpool, England, on Saturday Oct. 19, 2019, after the Letwin amendment, which seeks to avoid a no-deal Brexit on October 31, was accepted by the House, following Prime Minister Boris Johnson's statement in the House of Commons over his new Brexit deal. (Danny Lawson/PA via AP)
Labour Party leader Jeremy Corbyn and shadow education secretary Angela Rayner acknowledge supporters at the Grand Central Hall in Liverpool, England, on Saturday Oct. 19, 2019, after the Letwin amendment, which seeks to avoid a no-deal Brexit on October 31, was accepted by the House, following Prime Minister Boris Johnson's statement in the House of Commons over his new Brexit deal. (Danny Lawson/PA via AP)
Britain's opposition Liberal Democrat party leader Jo Swinson speaks during the Brexit debate inside the House of Commons parliament in London Saturday Oct. 19, 2019. At the rare weekend sitting of Parliament, Prime Minister Boris Johnson implored legislators to ratify the Brexit deal he struck this week with the other 27 EU leaders. Lawmakers voted Saturday in favour of the 'Letwin Amendment', which seeks to avoid a no-deal Brexit on October 31. (Stephen Pike/House of Commons via AP)
Lawmaker of SNP (Scottish National Party) Joanna Cherry speaks during the Brexit debate inside the House of Commons parliament in London Saturday Oct. 19, 2019. At the rare weekend sitting of Parliament, Prime Minister Boris Johnson implored legislators to ratify the Brexit deal he struck this week with the other 27 EU leaders. Lawmakers voted Saturday in favour of the 'Letwin Amendment', which seeks to avoid a no-deal Brexit on October 31. (Stephen Pike/House of Commons via AP)
Secretary of State for Exiting the European Union lawmaker Stephen Barclay speaks during the Brexit debate, watched by Prime Minister Boris Johnson, right, inside the House of Commons in London Saturday Oct. 19, 2019. At the rare weekend sitting of Parliament, Prime Minister Boris Johnson implored legislators to ratify the Brexit deal he struck this week with the other 27 EU leaders. Lawmakers voted Saturday in favour of the 'Letwin Amendment', which seeks to avoid a no-deal Brexit on October 31. (Jessica Taylor/House of Commons via AP)
Britain's Prime Minister Boris Johnson speaks during the Brexit debate inside the House of Commons in London Saturday Oct. 19, 2019. At the rare weekend sitting of Parliament, Prime Minister Boris Johnson implored legislators to ratify the Brexit deal he struck this week with the other 27 EU leaders. Lawmakers voted Saturday in favour of the 'Letwin Amendment', which seeks to avoid a no-deal Brexit on October 31. (Jessica Taylor/House of Commons via AP)
Anti-Brexit remain in the European Union supporters take part in a
Whippets wear clothing with the EU flag during anti-Brexit protests in London, Saturday, Oct. 19, 2019. Britain's Parliament is set to vote in a rare Saturday sitting on Prime Minister Boris Johnson's new deal with the European Union, a decisive moment in the prolonged bid to end the Brexit stalemate. Various scenarios may be put in motion by the vote. (AP Photo/Kirsty Wigglesworth)
A woman wears the colors and stars of the EU flag as she and other anti-Brexit supporters march in London, Saturday, Oct. 19, 2019. In their first weekend session in 37 years, British lawmakers in Parliament debated whether to accept Prime Minister Boris Johnson's proposed new divorce deal with the European Union. (AP Photo/Kirsty Wigglesworth)
Anti-Brexit demonstrators carry placards and EU flags in London, Saturday, Oct. 19, 2019. In their first weekend session in 37 years, British lawmakers in Parliament debated whether to accept Prime Minister Boris Johnson's proposed new divorce deal with the European Union. (AP Photo/Kirsty Wigglesworth)
Police officers watch as anti-Brexit protestors carry effigies of British Prime Minister Boris Johnson, right, and his top advisor Dominic Cummings, left, during a march in London, Saturday, Oct. 19, 2019. In a major blow to British Prime Minister Boris Johnson, U.K. lawmakers voted Saturday to postpone a decision on whether to back his Brexit deal with the European Union, throwing a wrench into government plans to leave the bloc at the end of this month. (AP Photo/Vudi Xhymshiti)