The lawmakers, long critical of May’s Brexit strategy to leave the EU which they believe is being driven by Conservative eurosceptics, said in a statement they would join a new group in parliament set up by seven former opposition Labour politicians, Reuters reported.
May said she was saddened by the resignations, but signaled she would press on with her attempts to win a deal before Britain is due to leave the bloc on March 29.
But the resignations put May in an even weaker position in parliament, where her Brexit deal was crushed by lawmakers last month when eurosceptics and EU supporters voted against an agreement that both sides say offers the worst of all worlds.
They could also undermine May’s negotiating position in Brussels, where she is going later on Wednesday for talks with Commission President Jean-Claude Juncker to try to secure an opening for further technical work on revising the agreement.
With only 37 days until Britain leaves the EU, its biggest foreign and trade policy shift in more than 40 years, divisions over Brexit are redrawing the political landscape. The resignations threaten a decades-old two-party system.
“The final straw for us has been this government’s disastrous handling of Brexit,” the three lawmakers, Heidi Allen, Anna Soubry and Sarah Wollaston, said in a statement.
“We no longer feel we can remain in the party of a government whose policies and priorities are so firmly in the grip of the ERG and DUP,” they said, referring to a group of Conservative pro-Brexit lawmakers and the Northern Irish Democratic Unionist Party which props up the government in parliament.
May acknowledged that Britain’s membership of the EU “has been a source of disagreement both in our party and in our country for a long time” adding that leaving the bloc “was never going to be easy”.
“But by delivering on our manifesto commitment and implementing the decision of the British people we are doing the right thing for our country. And in doing so, we can move forward together towards a brighter future,” she said.
The three said they would now sit with a new grouping in parliament that broke away from the Labour Party earlier this week over increasing frustration with their leader Jeremy Corbyn’s Brexit strategy and a row over anti-Semitism.
Another former Labour lawmaker joined their ranks late on Tuesday, and several politicians from both the main opposition party and Conservatives said they expected more to follow from both sides of parliament.
For May’s Brexit plan, the resignations are yet another blow to more than two years of talks to leave the EU, which have been punctuated by defeats in parliament, rows over policy and a confidence vote, which she ultimately won.
Britain’s 2016 EU referendum, when 52 percent voted to leave versus 48 to remain, has split not only British towns and villages but also parliament, with both Conservative and Labour leaders struggling to keep their parties united.
Trying to unite her party around her Brexit plan has been a difficult balancing act for the prime minister. Eurosceptic members of her party want a clean break with the bloc, pro-EU lawmakers argue for the closest possible ties, while many in the middle are increasing frustrated over the lack of movement.
Those who have resigned have long accused May of leaning too far towards Brexit supporters, sticking to red lines which they, and many in Labour, say have made a comprehensive deal all but impossible to negotiate.
But May will head to Brussels hoping that her team may get the green light to start more technical negotiations on how to satisfy the concerns of mostly Brexit supporters over the so-called Northern Irish backstop arrangement.
The “backstop”, an insurance policy to prevent the return of a hard border between the British province of Northern Ireland and EU member Ireland if the Brexit negotiations fail to come up with a future relationship to prevent it, is the main point of contention in ongoing talks with Brussels.
British officials are hoping they can secure the kind of legal assurances that the backstop cannot trap Britain in the EU’s sphere to persuade lawmakers to back a revised deal.
But May’s argument that she can command a majority in parliament if the EU hands her such assurances is getting weaker every day. A government defeat by eurosceptics on a symbolic vote last week showed their muscle, while the departure of some pro-EU lawmakers also undermines her position.
Reporting by Kylie Maclellan, William James and Elizabeth Piper; Writing by Elizabeth Piper; Editing by Stephen Addison and Raissa Kasolowsky