Boris Johnson has claimed any Brexit deal must involve the Irish backstop being abolished.
The new British prime minister has been addressing the House of Commons for the first time.
He repeated his pledge that the UK will leave the EU on October 31st, with or without a deal.
The EU has ruled out renegotiating the withdrawal agreement - but Mr Johnson insists he's determined to get a new deal.
However, he called for the backstop - the 'insurance policy' aimed at avoiding a hard border in Ireland - to be scrapped.
He told MPs: "A time limit is not enough - if an agreement is to be reached, it must be clearly understood that the way to the deal goes by the abolition of the backstop.
"For our part, we are ready to negotiate in good faith an alternative - with provisions to ensure the Irish border issues are dealt with, where they should always have been: in negotiations on the future agreement between the UK and the EU."
Mr Johnson also said cabinet minister Michael Gove has been tasked with "turbo-charging" no-deal planning.
Labour leader Jeremy Corbyn, meanwhile, suggested there's something "eerily familiar" about a prime minister "marching off to Europe" to demand an end to the backstop.
The opposition leader asked: "How does the prime minister think he will succeed where his predecessor failed?"