The EU’s chief negotiator Michel Barnier stressed the urgency of Brexit talks ahead of a meeting with Prime Minister Theresa May on Monday, with her government still deeply divided on the negotiations. 

“My feeling is that we have not a minute to lose because we want to achieve a deal,” Barnier told the BBC and Sky News television as he left for London.

Barnier will also meet the UK’s Brexit minister David Davis ahead of talks between British and European Union officials in Brussels from Tuesday to Friday.

Reports in recent days that some government ministers will seek to keep Britain in a customs union with the EU in order to safeguard trade ties have raised tensions between pro-EU and pro-Brexit factions.

But ahead of Barnier’s visit, May’s spokesman said that Britain did not want to be in a customs union with the EU once it leaves the bloc.

“It is not the government’s policy to be a member of the customs union or a customs union,” he told a daily briefing on Monday, saying the two options were instead “a new customs partnership” or “a highly streamlined customs arrangement”.

London and Brussels struck a preliminary deal on key Brexit issues in December but are yet to discuss the conditions for a post-Brexit transition period and future trade relations.

‘Surprise for the Brexiteers’

May has yet to bring together her divided government to produce a final plan.

High-profile pro-Brexit ministers Boris Johnson and Michael Gove are later this week set for a cabinet meeting showdown with europhile ministers, led by finance minister Philip Hammond, as they battle to shape Britain’s post-Brexit vision.

Johnson and Gove are ready to deliver an ultimatum to prevent May backtracking on plans to fully leave the customs union, according to The Sunday Times.

Brexit supporters within May’s Conservative Party would be prepared to replace the premier with Johnson and install Gove as his deputy, with influential backbencher Jacob Rees-Mogg drafted in as finance minister, the newspaper reported.

Such a move would enrage the sizeable rump of hardcore pro-EU Conservative MPs, raising the spectre of another general election as May is running a minority government.

The internal tensions exploded into public view last week when Rees-Mogg, who is the bookmaker’s favourite to become the next Conservative Party leader, accused Hammond’s department of “fiddling the books” in providing gloomy forecasts of Brexit’s economic impact.

Conservative MP and Brexit supporter Bernard Jenkin wrote in The Sunday Telegraph newspaper that May “can only command a majority in parliament on her present policy” — a thinly veiled threat that Brexiteers would be prepared to bring down her vulnerable government.

Pro-EU interior minister Amber Rudd hit back on Sunday, telling BBC television: “I have a surprise for the Brexiteers, which is the committee that meets in order to help make these decisions is more united than they think.”

‘Must apply all the rules’

Britain voted to leave the European Union in a momentous referendum in June 2016 that revealed a bitterly divided nation, sparked a tumultuous period in British politics and caused global shockwaves.

Although Britain will officially leave the bloc in March next year, it hopes to secure a two-year transition deal to taper the effects of Brexit.

Terms of the transition deal will be on the negotiating table this week, with key issues up for debate including immigration, Britain’s ability to strike third-party trade deals, and whether Britain will have to abide by new EU laws.

Barnier has said that Britain “will continue to have all the economic benefits, therefore it must apply all the rules” during this transition period.

However, May appears set on a collision course with the EU after questioning the rights of EU citizens who arrive in Britain during the transition.

May insisted Friday she was “doing what the British people want” and going nowhere despite pressure on her to resign.