Nick Boles, 53, has been critical of the government's threat to leave the EU without a deal and has faced calls from his local party to be ousted as its candidate for the next general election. Boles said he could remain aligned with the Conservatives in parliament if they make him an acceptable offer.
The former minister said in a letter to his local party he was "not willing to do what would be necessary to restore a reasonable working relationship with a group of people whose values and views are so much at odds with my own." "I regret that my relationship with you should end in this way. But a politician without principles is worthless."
Britain’s 2016 EU referendum has split not only British towns and villages but also parliament, with both Conservative and Labour leaders struggling to keep their parties united. Last month, eleven members of parliament from both main parties defected to form the Independent Group, in large part dismayed by the handling of Brexit.
This week, lawmakers voted down Prime Minister Theresa May's divorce deal with the EU for a second time - by 391 to 242. Boles backed May, but has urged the government to work with opposition parties on an alternative Brexit plan - which would likely lead to a closer relationship with the EU than many Conservatives are prepared to accept.
May continues to fight to build support for her plan, which is expected to put before lawmakers for a third time next week. (Reporting by Andrew MacAskill; Editing by Mark Potter)