LONDON (Reuters) – Prime Minister Theresa May said on Sunday that Britain would be in uncharted territory if her Brexit deal is rejected by parliament later this month, despite little sign that she has won over sceptical lawmakers.

Britain is due to leave the EU on March 29 but May’s inability so far to get her deal for a managed exit through parliament has alarmed business leaders and investors who fear the country is heading for an damaging no-deal Brexit.

May said the vote in parliament would be around Jan. 15, despite newspaper reports she could delay it. May has already delayed the vote once, in December, when it became clear she would lose unless extra reassurances from the EU were agreed.

Describing what would happen if she was defeated, May told the BBC: “We’re going to be in uncharted territory. I don’t think anybody can say exactly what will happen in terms of the reaction we’ll see in parliament.”

May’s party is divided over its support for the deal, with many fearing that an insurance policy designed to avoid the re-emergence of a hard border between Ireland and Northern Ireland could leave Britain subject to EU rules indefinitely.

One of those leading that opposition, lawmaker Jacob Rees-Mogg, said in a newspaper article that it was “wishful thinking” that time away from parliament over the Christmas holiday could persuade him to change his mind and back the deal.