May wants to refocus attention on Brexit talks following a disastrous speech at last week's Tory conference. The EU is insisting that until "sufficient progress" is made on that issue, along with citizens' rights and the Irish border, it will not open up talks about the future, something the European commission had originally planned to happen at a summit in Brussels on 19 October.
A fifth round of talks between British and European Union officials began Monday in Brussels.
May's office says she will say Monday that "the ball is in their court".
However heavy-weight member states link any willingness to talk about a transition period of possibly two years after 2019 to having more clarity on the financial deal with the UK.
Responding to renewed suggestions from May's government that Britain could simply leave the European Union in March 2019 without a negotiated settlement, Tusk said the European Union was not working on a "no deal" scenario.
A spokeswoman from May's office said she restated her position "that the government's goal is for a smooth, orderly exit in which there is only one set of changes for businesses and people".
After an interim period, which should contain a "new and time-limited customs union between the United Kingdom and the EU" to replace the current customs union, the British government has outlined two options.
Last week, two sources told Reuters that Japanese carmaker Toyota meant to build the next version of its Auris auto at its British vehicle plant on the assumption that the government secures a transitional Brexit deal in a decision due by the end of the year.
Instead, she can only do what the anti-EU, pro-hard Brexit wing of her Conservative party wants, which is to surrender very little ground and refuse to offer up any significant details about the divorce bill. "I am sure that we will get a positive response because we are striving to conclude not only the best possible agreement for us but also the best deal for our European friends,". The EU27 are adamant that all phase one issues must be addressed to their satisfaction before any talk of the future relationship.
When asked about her plans for Johnson in a cabinet shake-up, the prime minister said: "It has never been my style to hide from a challenge, and I'm not going to start now".
"I think a growing number of my colleagues realise the solution isn't to bury our heads in the sand and hope things will get better..."
This comes after government claims emerged that Brexit is now "unstoppable", suggesting that MPs may be forced into agreeing to a bad deal no matter how damaging it could be for the UK.
Leslie, a former shadow chancellor, told BuzzFeed News: "It might be inconvenient for the prime minister and it might go against government policy, but if she knows that legal advice says the Article 50 notice can be reversed she should stop dodging the question and be straight with Parliament on this".