Tory leadership contender Esther McVey has said there will be no further extensions and the UK will leave the EU on October 31, with or without a deal.
The former work and pensions secretary told Sky's Sophy Ridge on Sunday that the UK must start preparing for a no-deal exit straight away.
She added: "October 31 is the key date and we are coming out then, and if that means without a deal then that's what it means.
"We won't be asking for any more extensions.
"If Europe wants to come back to us, the door is open if they want a better deal.
"Time is limited, we have to make sure we are ready to leave."
McVey also said she would use the growth in the international aid budget to boost school and police funding.
She said the aid budget has grown from £8 billion to £14 billion and while that would remain high under her leadership, she would use the growth to fund "radical changes".
She told the programme she would invest an extra £4 billion for schools and also said there needs to be an extra £3 billion for policing.
She added: "Obviously we have to live within our means, that will come from the extra amount that has gone into foreign aid.
"We are going to leave it at high levels, however we have got to look after people at home, particularly safety on the streets, particularly in schools and transport and the NHS.
"That's the vision we have got to set out and unite the country and our party."
Speaking outside his home in west London, Environment Secretary Michael Gove said: "I can confirm that I will be putting my name forward to be prime minister of this country.
"I believe that I'm ready to unite the Conservative and Union Party, ready to deliver Brexit, and ready to lead this great country."
Former first secretary of state Damian Green told Sky News: "I think the next leader should be Matt Hancock.
"I do think we need a fresh start."
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