Brexit Secretary David Davis is to make a keynote speech in Germany amid signs of optimism the two sides in the Brexit negotiations are edging towards a breakthrough.
Mr Davis's address, to an economic summit in Berlin, comes after the EU chief negotiator Michel Barnier warned on Friday that progress was needed within two weeks if the talks were to move to the second phase before the end of the year.
Following the sixth round of negotiations in Brussels, Mr Barnier said they had to have greater clarity on key issues - including Britain's "divorce bill" - if EU leaders were to agree to open discussions on future relations, including a trade deal, at their December summit.
Meanwhile in Parliament on Wednesday, MPs continued to debate the EU (Withdrawal) Bill amid a row over The Daily Telegraph's labelling of Tory critics of the key legislation as "the Brexit mutineers".
Former minister Anna Soubry said her office had reported at least five threatening tweets to the police after being pictured on the front page of the newspaper.
In a letter to the Telegraph, 15 Conservative MPs hit back insisting they would continue to oppose the Government's attempt to enshrine the date of Britain's withdrawal from the EU in law, warning it could "accidentally harm our country's interest".
"Putting a date in law is too rigid. As negotiations reach their close, the Government may need a small amount of additional time to conclude, for example, the best transitional deal.
"We are pleased Conservative colleagues from across the Brexit divide accept our intentions are genuine and note that some are disappointed you didn't include them."
Elsewhere, a key ally of German Chancellor Angela Merkel emerged from meetings in London with Theresa May and Mr Davis on Wednesday saying that he was "more optimistic" about the prospects for a deal.
Manfred Weber, the senior German MEP who heads the main centre-right grouping in the European Parliament, said he was encouraged by the "positive atmosphere", although they were not yet ready for phase two.
"I am more optimistic. There is progress and a will to see progress," he said. "The atmosphere is positive but we need clear and concrete commitments to step into the second phase. For now the green light is not there."
On the financial settlement, Mr Weber said while the UK did not have to state a figure at this stage, it did need spell out which of its outstanding commitments to the EU it was prepared to honour.
"For the so-called sufficient progress question for the December council, the most important thing is not the figure. The most important thing is to clarify the commitments - the areas where Great Britain has to see its commitments," he said.
Failure to secure agreement at the December summit would be a major setback for the Prime Minister as the next opportunity for EU leaders to green light the second phase talks will not be until March.
It would almost certainly prompt demands from hardline Brexiteers for Mrs May to walk away from the negotiating table altogether.