Prime Minister Boris Johnson likened himself to the comic book character the Incredible Hulk in a newspaper interview where he stressed his determination to take Britain out of the European Union on October 31.
Nevertheless, Johnson told the Mail on Sunday he remains "very confident" of getting a new deal before the October 17 summit.
"The madder Hulk gets, the stronger Hulk gets and he always escaped, no matter how tightly bound in he seemed to be - and that is the case for this country", he said.
His comments came ahead of talks with European Commission chief Jean-Claude Juncker and the EU's chief Brexit negotiator, Michel Barnier, in Luxembourg on Monday.
Media reports from mainland Europe indicate that Johnson may face an uphill struggle securing the kind of deal he is seeking to bring Britain out of the bloc. "A huge amount of progress is being made", said Johnson, who succeeded May as British PM less than two months ago.
But Johnson is facing strong opposition in parliament to his threat to leave the European Union without a deal on October 31 if his negotiations fail.
David Cameron has launched another stinging attack on Boris Johnson, claiming the prime minister "didn't believe" in Brexit and only backed the Leave campaign to further his career.
Hard-line Brexiteers have signaled they would be willing to vote for a Brexit deal if Johnson can win meaningful concessions on the Northern Ireland backstop, according to the Sunday Times.
"Even to Trumpian requirements the Hulk comparability is childish", he tweeted.
Cameron's critics say the British public was never really clamouring for the 2016 referendum and that Cameron called it only to quell internal squabbles in his fractious Conservative Party and to quiet the rabid Tory tabloids.
Johnson and his ministers have in recent days talked up progress in negotiations with Brussels, but the European Union side have consistently sounded less optimistic, putting the emphasis on Britain to come up with new ideas.
Late Saturday, former universities minister Sam Gyimah joined the Liberal Democrats, accusing the prime minister of "playing fast and loose" with the constitution.
Brexit Secretary Steve Barclay said a "landing zone" for an agreement was in sight, telling Sky News's Sophy Ridge On Sunday that there had been "extensive talks" happening at both a technical and political level.
Support for Nigel Farage's Brexit Party remained at 13%.
Talks are still stalled on the contentious issue of the Irish border backstop, a policy meant to ensure there are no checks on goods crossing the U.K.'s land border with Ireland.
Britain's Prime Minister Boris Johnson reacts during the Convention of the North at the Magna Centre in Rotherham, Britain September 13, 2019. The defection further weakens Mr. Johnson's government, which has already lost its majority in the House of Commons.
"I can´t objectively tell you whether the contacts we have undertaken with Mr. Johnson´s government will lead to an agreement between now and mid-October", he said.
"It was the behaviour of the employment minister, Patel, that shocked me most", says Cameron in his book, which is serialised in "The Sunday Times".