FILE PHOTO: Pro-Brexit supporter and ex-Secretary of State for Exiting the European Union, David Davis addresses a 'Leave Means Leave' rally at the University of Bolton, in Bolton, Britain, September 22, 2018. REUTERS/Hannah McKay

LONDON (Reuters) - Prime Minister Theresa May’s ministers should “exert their collective authority” to force a change in her Brexit strategy, former Brexit minister David Davis said on Sunday, stepping up pressure on Britain’s leader.

In an article in the Sunday Times newspaper, Davis again pressed May to abandon her proposal for leaving the European Union, saying the bloc “has rejected it. The public does not like it. Parliament will not vote for it”.

With less than six months before Britain leaves the EU in its biggest trade and foreign policy shift in more than 40 years, May is struggling to get backing for not only her vision for future ties with the bloc but also over a so-called backstop deal for Northern Ireland, one of the trickiest hurdles left.

Talks with Brussels have been all but non-stop before a summit on Wednesday when the two sides hope to agree a draft withdrawal treaty to outline the divorce terms, including a transition agreement and a solution to Northern Ireland.

Davis, who again criticized the government of which he was once part for accepting “the EU’s language on dealing with the Northern Ireland border” in December, said it was now up to the so-called cabinet of top ministers to exert their influence.

“This is one of the most fundamental decisions that government has taken in modern times. It is time for cabinet members to exert their collective authority,” Davis wrote.

“This week the authority of our constitution is on the line.”

Davis also said Britain should use the 39 billion pounds Britain has agreed in a financial settlement with the EU as the “biggest bargaining chip” to secure a beneficial future trading relationship with the bloc.