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.

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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 LawsonPA via 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.

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 LawsonPA via AP)

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.

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 PikeHouse 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 PikeHouse 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 TaylorHouse 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 TaylorHouse of Commons via AP)

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 PhotoVudi Xhymshiti)

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 PhotoVudi Xhymshiti)

EU officials have not responded to the request.

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 LawsonPA 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 LawsonPA via AP)

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.

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 LawsonPA 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 LawsonPA 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 PikeHouse 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 PikeHouse 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 TaylorHouse 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 TaylorHouse of Commons via AP)

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 PhotoVudi Xhymshiti)

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 PhotoVudi Xhymshiti)