LONDON (Reuters) - Opponents of Prime Minister Theresa May’s Brexit plans called on her cabinet ministers on Tuesday to vote down an agreement on Britain’s withdrawal terms if it bore any resemblance to reports of the deal they had seen.

At an impromptu news conference in parliament, eurosceptic Conservative lawmaker Jacob Rees-Mogg said his group of pro-Brexit politicians in parliament believed that the so-called backstop arrangement to prevent the return of a hard border on the island of Ireland would make Britain a “slave” state.

Nigel Dodds, deputy leader of the small Northern Irish party which props up May’s government, said he needed to see the terms of what officials have called an agreement on the technical terms of the withdrawal deal to decide whether to pull the party’s support, but that he had his concerns.