LONDON (AP) — Former British Foreign Secretary Boris Johnson has compared Prime Minister Theresa May's plan for Brexit to putting the country's constitution in a "suicide vest" and handing the detonator to the European Union.

The attack, and Johnson's choice of language, widened the divide in the governing Conservative Party over Brexit.

Johnson, a strong supporter of Brexit, quit May's government in July after rejecting her proposal for close economic ties with the bloc after the U.K. leaves next year. His article in the Mail on Sunday ramped up speculation that he plans to challenge her leadership.

But some Conservative colleagues condemned his language.

Foreign Office Minister Alan Duncan tweeted that the comments marked "one of the most disgusting moments in modern British politics" and should be "the political end of Boris Johnson."