When an extension to Article 50 was agreed in April, giving the United Kingdom until 31 October to ratify the Brexit deal, Mr Tusk pleaded with British politicians: "Do not waste this time".
European Union leaders are underlining that their divorce agreement with Britain can not be renegotiated regardless of who becomes the next prime minister there.
Both are backing Boris Johnson in the race for 10 Downing Street.
"It should be obvious to everyone that what Britain does not need is another prime minister who wastes yet more time trying to fiddle with this miserable deal".
Whoever triumphs, the new prime minister will try to wring a tweaked Brexit withdrawal deal more palatable to British politicians from a sceptical Brussels that has said there will be no further negotiation over the agreement.
"That has not been done yet and I don't see that being done this side of October 31", Varadkar told reporters, insisting the backstop must stay.
Love Island viewers divided over Yewande and Danny After storming off from a heated conversation with Arabella, Yewande told others in the villa: "I am f****** fuming". Arabella's claim to fame is a movie she filmed with Jason Momoa who she says is her celebrity crush.
Recent threats by Johnson to withhold Britain's 39-billion-pound (44-million-euro, $50-million) divorce bill unless the European Union agrees to better terms were seen in Brussels as a sign of possible bad faith.
Most economists think a sharp rupture with the European Union, which accounts for around 50% of Britain's trade, will lead to a deep recession.
The current deal has been rejected three times by the British parliament, and if Johnson or Hunt can not get it or another version passed, investors worry Britain will leave the European Union on October 31 without transitional trading arrangements in place with its largest trading partner.
Mr. Johnson has said Britain can rely on a provision in worldwide trade rules to make sure trade relations remain unchanged.
Carney, who has previously warned about the economic impact of a no-deal Brexit, made the comment in an interview with the BBC, an excerpt of which was broadcast on Friday.
"We should be clear that no deal means no deal - it means there is a substantial change in the trading relationship with the EU".