Theresa May will warn today that Brussels has adopted an “aggressive negotiating position” for talks that will begin just eleven days after the election.

Ms May has long argued that only she, and not Jeremy Corbyn, is capable of leading Britain’s negotiations with Brussels, a point she will make again on Tuesday in a speech in the West Midlands.

The Conservatives have highlighted the most recent EU negotiating guidelines released by the European Commission, including mention of the so-called "divorce bill" which calls for a "single financial settlement" covering all the UK's outstanding liabilities.

"This single financial settlement should be based on the principle that the United Kingdom must honour its share of the financing of all the obligations undertaken while it was a member of the Union," the paper said.

The EU has not yet set out what it considers a fair sum, with varying reports indicating anywhere between £20bn and £90bn. Brexit Secretary David Davis has said “even £1bn is a lot.”

In her speech, Mrs May is expected to say: "The European Commission has shown the importance of the choice faced by the British public next week.

"They are adopting an aggressive negotiating position, which can only be met by strong leadership on behalf of Britain.

"Jeremy Corbyn is in no position to provide that kind of leadership. He has no plan to deliver Brexit, and he has already admitted he would give control of our borders and control of our laws back to Brussels."

The Conservative campaign chief Sir Lynton Crosby is understood to have told the party to refocus on the issue of Brexit, after the disastrous social care policy announcement and subsequent U-turn, branded the ‘dementia tax.’