"I think it's going to be very difficult to secure an agreement by next week, quite frankly," Varadkar told Irish broadcaster RTE late Tuesday after a 40-minute phone call with British Prime Minister Boris Johnson.
"Essentially what the United Kingdom has done is repudiate the deal that we negotiated in good faith with Prime Minister (Theresa) May's government over two years and have sort of put half of that now back on the table and are saying, 'That's a concession'. And, of course, it isn't really."
The comments contradicted Johnson's office, which said Tuesday that EU intransigence had led to a breakdown in negotiations. The U.K. said, however, that it still hopes to strike a deal. Johnson and Varadkar are expected to meet in person later this week.
Johnson says Britain will leave without a negotiated settlement if a deal can't be reached by the Brexit deadline of Oct. 31. The Times of London reported Wednesday that five Cabinet ministers are threatening to resign if the Conservative government adopts a no-deal Brexit as its central policy.
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This story has been corrected to show that the Irish prime minister's last name is Varadkar, not Varadkhar.