British Prime Minister Theresa May's Conservative Party faces a "catastrophic split" if she persists with her so-called Chequers proposals on Brexit and 80 or more of her lawmakers are prepared to vote against the proposals, a former junior minister said.

Such public criticism, just a day after her former foreign minister, Boris Johnson, branded her Brexit plans as "a suicide vest" wrapped around the British constitution, indicates the level of opposition to her within the party.

Steve Baker, a former junior Brexit minister who resigned over May's Brexit proposals, told the Press Association that he was not advocating a change of leader but warned that May faces a massive problem at the Sept. 30-Oct. 3 party conference.