Theresa May has insisted she can achieve a “smooth and orderly Brexit”, at a press conference with Angela Merkel on a day when two Conservative party vice-chairs resigned in protest at her soft Brexit negotiating plan.

The prime minister sought to reassert her authority over her party as she appeared with the German chancellor, but she also had to fend off questions about whether Donald Trump was right to suggest the UK was in “turmoil”.

May looked uncomfortable as she addressed journalists at the press conference but she said the Brexit white paper expected on Thursday would keep “faith with the vote of the British people” and the UK would depart the EU in a “smooth and orderly” manner.